diff --git a/base/numerics/BUILD.gn b/base/numerics/BUILD.gn
new file mode 100644
index 0000000..0bb8dd1
--- /dev/null
+++ b/base/numerics/BUILD.gn
@@ -0,0 +1,28 @@
+# Copyright (c) 2017 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This is a dependency-free, header-only, library, and it needs to stay that
+# way to facilitate pulling it into various third-party projects. So, this
+# file is here to protect against accidentally introducing external
+# dependencies or depending on internal implementation details.
+source_set("base_numerics") {
+  visibility = [ "//base/*" ]
+  sources = [
+    "checked_math_impl.h",
+    "clamped_math_impl.h",
+    "safe_conversions_arm_impl.h",
+    "safe_conversions_impl.h",
+    "safe_math_arm_impl.h",
+    "safe_math_clang_gcc_impl.h",
+    "safe_math_shared_impl.h",
+  ]
+  public = [
+    "checked_math.h",
+    "clamped_math.h",
+    "math_constants.h",
+    "ranges.h",
+    "safe_conversions.h",
+    "safe_math.h",
+  ]
+}
diff --git a/base/numerics/DEPS b/base/numerics/DEPS
new file mode 100644
index 0000000..d95bf13
--- /dev/null
+++ b/base/numerics/DEPS
@@ -0,0 +1,7 @@
+# This is a dependency-free, header-only, library, and it needs to stay that
+# way to facilitate pulling it into various third-party projects. So, this
+# file is here to protect against accidentally introducing dependencies.
+include_rules = [
+  "-base",
+  "+base/numerics",
+]
diff --git a/base/numerics/OWNERS b/base/numerics/OWNERS
new file mode 100644
index 0000000..5493fba
--- /dev/null
+++ b/base/numerics/OWNERS
@@ -0,0 +1,5 @@
+jschuh@chromium.org
+tsepez@chromium.org
+
+
+# COMPONENT: Internals
diff --git a/base/numerics/README.md b/base/numerics/README.md
new file mode 100644
index 0000000..896b124
--- /dev/null
+++ b/base/numerics/README.md
@@ -0,0 +1,409 @@
+# `base/numerics`
+
+This directory contains a dependency-free, header-only library of templates
+providing well-defined semantics for safely and performantly handling a variety
+of numeric operations, including most common arithmetic operations and
+conversions.
+
+The public API is broken out into the following header files:
+
+*   `checked_math.h` contains the `CheckedNumeric` template class and helper
+    functions for performing arithmetic and conversion operations that detect
+    errors and boundary conditions (e.g. overflow, truncation, etc.).
+*   `clamped_math.h` contains the `ClampedNumeric` template class and
+    helper functions for performing fast, clamped (i.e. non-sticky saturating)
+    arithmetic operations and conversions.
+*   `safe_conversions.h` contains the `StrictNumeric` template class and
+    a collection of custom casting templates and helper functions for safely
+    converting between a range of numeric types.
+*   `safe_math.h` includes all of the previously mentioned headers.
+
+*** aside
+**Note:** The `Numeric` template types implicitly convert from C numeric types
+and `Numeric` templates that are convertable to an underlying C numeric type.
+The conversion priority for `Numeric` type coercions is:
+
+*   `StrictNumeric` coerces to `ClampedNumeric` and `CheckedNumeric`
+*   `ClampedNumeric` coerces to `CheckedNumeric`
+***
+
+[TOC]
+
+## Common patterns and use-cases
+
+The following covers the preferred style for the most common uses of this
+library. Please don't cargo-cult from anywhere else. 😉
+
+### Performing checked arithmetic conversions
+
+The `checked_cast` template converts between arbitrary arithmetic types, and is
+used for cases where a conversion failure should result in program termination:
+
+```cpp
+// Crash if signed_value is out of range for buff_size.
+size_t buff_size = checked_cast<size_t>(signed_value);
+```
+
+### Performing saturated (clamped) arithmetic conversions
+
+The `saturated_cast` template converts between arbitrary arithmetic types, and
+is used in cases where an out-of-bounds source value should be saturated to the
+corresponding maximum or minimum of the destination type:
+
+```cpp
+// Convert from float with saturation to INT_MAX, INT_MIN, or 0 for NaN.
+int int_value = saturated_cast<int>(floating_point_value);
+```
+
+### Enforcing arithmetic conversions at compile-time
+
+The `strict_cast` enforces type restrictions at compile-time and results in
+emitted code that is identical to a normal `static_cast`. However, a
+`strict_cast` assignment will fail to compile if the destination type cannot
+represent the full range of the source type:
+
+```cpp
+// Throw a compiler error if byte_value is changed to an out-of-range-type.
+int int_value = strict_cast<int>(byte_value);
+```
+
+You can also enforce these compile-time restrictions on function parameters by
+using the `StrictNumeric` template:
+
+```cpp
+// Throw a compiler error if the size argument cannot be represented by a
+// size_t (e.g. passing an int will fail to compile).
+bool AllocateBuffer(void** buffer, StrictCast<size_t> size);
+```
+
+### Comparing values between arbitrary arithmetic types
+
+Both the `StrictNumeric` and `ClampedNumeric` types provide well defined
+comparisons between arbitrary arithmetic types. This allows you to perform
+comparisons that are not legal or would trigger compiler warnings or errors
+under the normal arithmetic promotion rules:
+
+```cpp
+bool foo(unsigned value, int upper_bound) {
+  // Converting to StrictNumeric allows this comparison to work correctly.
+  if (MakeStrictNum(value) >= upper_bound)
+    return false;
+```
+
+*** note
+**Warning:** Do not perform manual conversions using the comparison operators.
+Instead, use the cast templates described in the previous sections, or the
+constexpr template functions `IsValueInRangeForNumericType` and
+`IsTypeInRangeForNumericType`, as these templates properly handle the full range
+of corner cases and employ various optimizations.
+***
+
+### Calculating a buffer size (checked arithmetic)
+
+When making exact calculations—such as for buffer lengths—it's often necessary
+to know when those calculations trigger an overflow, undefined behavior, or
+other boundary conditions. The `CheckedNumeric` template does this by storing
+a bit determining whether or not some arithmetic operation has occured that
+would put the variable in an "invalid" state. Attempting to extract the value
+from a variable in an invalid state will trigger a check/trap condition, that
+by default will result in process termination.
+
+Here's an example of a buffer calculation using a `CheckedNumeric` type (note:
+the AssignIfValid method will trigger a compile error if the result is ignored).
+
+```cpp
+// Calculate the buffer size and detect if an overflow occurs.
+size_t size;
+if (!CheckAdd(kHeaderSize, CheckMul(count, kItemSize)).AssignIfValid(&size)) {
+  // Handle an overflow error...
+}
+```
+
+### Calculating clamped coordinates (non-sticky saturating arithmetic)
+
+Certain classes of calculations—such as coordinate calculations—require
+well-defined semantics that always produce a valid result on boundary
+conditions. The `ClampedNumeric` template addresses this by providing
+performant, non-sticky saturating arithmetic operations.
+
+Here's an example of using a `ClampedNumeric` to calculate an operation
+insetting a rectangle.
+
+```cpp
+// Use clamped arithmetic since inset calculations might overflow.
+void Rect::Inset(int left, int top, int right, int bottom) {
+  origin_ += Vector2d(left, top);
+  set_width(ClampSub(width(), ClampAdd(left, right)));
+  set_height(ClampSub(height(), ClampAdd(top, bottom)));
+}
+```
+
+*** note
+The `ClampedNumeric` type is not "sticky", which means the saturation is not
+retained across individual operations. As such, one arithmetic operation may
+result in a saturated value, while the next operation may then "desaturate"
+the value. Here's an example:
+
+```cpp
+ClampedNumeric<int> value = INT_MAX;
+++value;  // value is still INT_MAX, due to saturation.
+--value;  // value is now (INT_MAX - 1), because saturation is not sticky.
+```
+
+***
+
+## Conversion functions and StrictNumeric<> in safe_conversions.h
+
+This header includes a collection of helper `constexpr` templates for safely
+performing a range of conversions, assignments, and tests.
+
+### Safe casting templates
+
+*   `as_signed()` - Returns the supplied integral value as a signed type of
+    the same width.
+*   `as_unsigned()` - Returns the supplied integral value as an unsigned type
+    of the same width.
+*   `checked_cast<>()` - Analogous to `static_cast<>` for numeric types, except
+    that by default it will trigger a crash on an out-of-bounds conversion (e.g.
+    overflow, underflow, NaN to integral) or a compile error if the conversion
+    error can be detected at compile time. The crash handler can be overridden
+    to perform a behavior other than crashing.
+*   `saturated_cast<>()` - Analogous to `static_cast` for numeric types, except
+    that it returns a saturated result when the specified numeric conversion
+    would otherwise overflow or underflow. An NaN source returns 0 by
+    default, but can be overridden to return a different result.
+*   `strict_cast<>()` - Analogous to `static_cast` for numeric types, except
+    this causes a compile failure if the destination type is not large
+    enough to contain any value in the source type. It performs no runtime
+    checking and thus introduces no runtime overhead.
+
+### Other helper and conversion functions
+
+*   `IsValueInRangeForNumericType<>()` - A convenience function that returns
+    true if the type supplied as the template parameter can represent the value
+    passed as an argument to the function.
+*   `IsTypeInRangeForNumericType<>()` - A convenience function that evaluates
+    entirely at compile-time and returns true if the destination type (first
+    template parameter) can represent the full range of the source type
+    (second template parameter).
+*   `IsValueNegative()` - A convenience function that will accept any
+    arithmetic type as an argument and will return whether the value is less
+    than zero. Unsigned types always return false.
+*   `SafeUnsignedAbs()` - Returns the absolute value of the supplied integer
+    parameter as an unsigned result (thus avoiding an overflow if the value
+    is the signed, two's complement minimum).
+
+### StrictNumeric<>
+
+`StrictNumeric<>` is a wrapper type that performs assignments and copies via
+the `strict_cast` template, and can perform valid arithmetic comparisons
+across any range of arithmetic types. `StrictNumeric` is the return type for
+values extracted from a `CheckedNumeric` class instance. The raw numeric value
+is extracted via `static_cast` to the underlying type or any type with
+sufficient range to represent the underlying type.
+
+*   `MakeStrictNum()` - Creates a new `StrictNumeric` from the underlying type
+    of the supplied arithmetic or StrictNumeric type.
+*   `SizeT` - Alias for `StrictNumeric<size_t>`.
+
+## CheckedNumeric<> in checked_math.h
+
+`CheckedNumeric<>` implements all the logic and operators for detecting integer
+boundary conditions such as overflow, underflow, and invalid conversions.
+The `CheckedNumeric` type implicitly converts from floating point and integer
+data types, and contains overloads for basic arithmetic operations (i.e.: `+`,
+`-`, `*`, `/` for all types and `%`, `<<`, `>>`, `&`, `|`, `^` for integers).
+However, *the [variadic template functions
+](#CheckedNumeric_in-checked_math_h-Non_member-helper-functions)
+are the prefered API,* as they remove type ambiguities and help prevent a number
+of common errors. The variadic functions can also be more performant, as they
+eliminate redundant expressions that are unavoidable with the with the operator
+overloads. (Ideally the compiler should optimize those away, but better to avoid
+them in the first place.)
+
+Type promotions are a slightly modified version of the [standard C/C++ numeric
+promotions
+](http://en.cppreference.com/w/cpp/language/implicit_conversion#Numeric_promotions)
+with the two differences being that *there is no default promotion to int*
+and *bitwise logical operations always return an unsigned of the wider type.*
+
+### Members
+
+The unary negation, increment, and decrement operators are supported, along
+with the following unary arithmetic methods, which return a new
+`CheckedNumeric` as a result of the operation:
+
+*   `Abs()` - Absolute value.
+*   `UnsignedAbs()` - Absolute value as an equal-width unsigned underlying type
+    (valid for only integral types).
+*   `Max()` - Returns whichever is greater of the current instance or argument.
+    The underlying return type is whichever has the greatest magnitude.
+*   `Min()` - Returns whichever is lowest of the current instance or argument.
+    The underlying return type is whichever has can represent the lowest
+    number in the smallest width (e.g. int8_t over unsigned, int over
+    int8_t, and float over int).
+
+The following are for converting `CheckedNumeric` instances:
+
+*   `type` - The underlying numeric type.
+*   `AssignIfValid()` - Assigns the underlying value to the supplied
+    destination pointer if the value is currently valid and within the
+    range supported by the destination type. Returns true on success.
+*   `Cast<>()` - Instance method returning a `CheckedNumeric` derived from
+    casting the current instance to a `CheckedNumeric` of the supplied
+    destination type.
+
+*** aside
+The following member functions return a `StrictNumeric`, which is valid for
+comparison and assignment operations, but will trigger a compile failure on
+attempts to assign to a type of insufficient range. The underlying value can
+be extracted by an explicit `static_cast` to the underlying type or any type
+with sufficient range to represent the underlying type.
+***
+
+*   `IsValid()` - Returns true if the underlying numeric value is valid (i.e.
+    has not wrapped or saturated and is not the result of an invalid
+    conversion).
+*   `ValueOrDie()` - Returns the underlying value. If the state is not valid
+    this call will trigger a crash by default (but may be overridden by
+    supplying an alternate handler to the template).
+*   `ValueOrDefault()` - Returns the current value, or the supplied default if
+    the state is not valid (but will not crash).
+
+**Comparison operators are explicitly not provided** for `CheckedNumeric`
+types because they could result in a crash if the type is not in a valid state.
+Patterns like the following should be used instead:
+
+```cpp
+// Either input or padding (or both) may be arbitrary sizes.
+size_t buff_size;
+if (!CheckAdd(input, padding, kHeaderLength).AssignIfValid(&buff_size) ||
+     buff_size >= kMaxBuffer) {
+  // Handle an error...
+} else {
+  // Do stuff on success...
+}
+```
+
+### Non-member helper functions
+
+The following variadic convenience functions, which accept standard arithmetic
+or `CheckedNumeric` types, perform arithmetic operations, and return a
+`CheckedNumeric` result. The supported functions are:
+
+*   `CheckAdd()` - Addition.
+*   `CheckSub()` - Subtraction.
+*   `CheckMul()` - Multiplication.
+*   `CheckDiv()` - Division.
+*   `CheckMod()` - Modulus (integer only).
+*   `CheckLsh()` - Left integer shift (integer only).
+*   `CheckRsh()` - Right integer shift (integer only).
+*   `CheckAnd()` - Bitwise AND (integer only with unsigned result).
+*   `CheckOr()`  - Bitwise OR (integer only with unsigned result).
+*   `CheckXor()` - Bitwise XOR (integer only with unsigned result).
+*   `CheckMax()` - Maximum of supplied arguments.
+*   `CheckMin()` - Minimum of supplied arguments.
+
+The following wrapper functions can be used to avoid the template
+disambiguator syntax when converting a destination type.
+
+*   `IsValidForType<>()` in place of: `a.template IsValid<>()`
+*   `ValueOrDieForType<>()` in place of: `a.template ValueOrDie<>()`
+*   `ValueOrDefaultForType<>()` in place of: `a.template ValueOrDefault<>()`
+
+The following general utility methods is are useful for converting from
+arithmetic types to `CheckedNumeric` types:
+
+*   `MakeCheckedNum()` - Creates a new `CheckedNumeric` from the underlying type
+    of the supplied arithmetic or directly convertible type.
+
+## ClampedNumeric<> in clamped_math.h
+
+`ClampedNumeric<>` implements all the logic and operators for clamped
+(non-sticky saturating) arithmetic operations and conversions. The
+`ClampedNumeric` type implicitly converts back and forth between floating point
+and integer data types, saturating on assignment as appropriate. It contains
+overloads for basic arithmetic operations (i.e.: `+`, `-`, `*`, `/` for
+all types and `%`, `<<`, `>>`, `&`, `|`, `^` for integers) along with comparison
+operators for arithmetic types of any size. However, *the [variadic template
+functions
+](#ClampedNumeric_in-clamped_math_h-Non_member-helper-functions)
+are the prefered API,* as they remove type ambiguities and help prevent
+a number of common errors. The variadic functions can also be more performant,
+as they eliminate redundant expressions that are unavoidable with the operator
+overloads. (Ideally the compiler should optimize those away, but better to avoid
+them in the first place.)
+
+Type promotions are a slightly modified version of the [standard C/C++ numeric
+promotions
+](http://en.cppreference.com/w/cpp/language/implicit_conversion#Numeric_promotions)
+with the two differences being that *there is no default promotion to int*
+and *bitwise logical operations always return an unsigned of the wider type.*
+
+*** aside
+Most arithmetic operations saturate normally, to the numeric limit in the
+direction of the sign. The potentially unusual cases are:
+
+*   **Division:** Division by zero returns the saturated limit in the direction
+    of sign of the dividend (first argument). The one exception is 0/0, which
+	returns zero (although logically is NaN).
+*   **Modulus:** Division by zero returns the dividend (first argument).
+*   **Left shift:** Non-zero values saturate in the direction of the signed
+    limit (max/min), even for shifts larger than the bit width. 0 shifted any
+    amount results in 0.
+*   **Right shift:** Negative values saturate to -1. Positive or 0 saturates
+    to 0. (Effectively just an unbounded arithmetic-right-shift.)
+*   **Bitwise operations:** No saturation; bit pattern is identical to
+    non-saturated bitwise operations.
+***
+
+### Members
+
+The unary negation, increment, and decrement operators are supported, along
+with the following unary arithmetic methods, which return a new
+`ClampedNumeric` as a result of the operation:
+
+*   `Abs()` - Absolute value.
+*   `UnsignedAbs()` - Absolute value as an equal-width unsigned underlying type
+    (valid for only integral types).
+*   `Max()` - Returns whichever is greater of the current instance or argument.
+    The underlying return type is whichever has the greatest magnitude.
+*   `Min()` - Returns whichever is lowest of the current instance or argument.
+    The underlying return type is whichever has can represent the lowest
+    number in the smallest width (e.g. int8_t over unsigned, int over
+    int8_t, and float over int).
+
+The following are for converting `ClampedNumeric` instances:
+
+*   `type` - The underlying numeric type.
+*   `RawValue()` - Returns the raw value as the underlying arithmetic type. This
+    is useful when e.g. assigning to an auto type or passing as a deduced
+    template parameter.
+*   `Cast<>()` - Instance method returning a `ClampedNumeric` derived from
+    casting the current instance to a `ClampedNumeric` of the supplied
+    destination type.
+
+### Non-member helper functions
+
+The following variadic convenience functions, which accept standard arithmetic
+or `ClampedNumeric` types, perform arithmetic operations, and return a
+`ClampedNumeric` result. The supported functions are:
+
+*   `ClampAdd()` - Addition.
+*   `ClampSub()` - Subtraction.
+*   `ClampMul()` - Multiplication.
+*   `ClampDiv()` - Division.
+*   `ClampMod()` - Modulus (integer only).
+*   `ClampLsh()` - Left integer shift (integer only).
+*   `ClampRsh()` - Right integer shift (integer only).
+*   `ClampAnd()` - Bitwise AND (integer only with unsigned result).
+*   `ClampOr()`  - Bitwise OR (integer only with unsigned result).
+*   `ClampXor()` - Bitwise XOR (integer only with unsigned result).
+*   `ClampMax()` - Maximum of supplied arguments.
+*   `ClampMin()` - Minimum of supplied arguments.
+
+The following is a general utility method that is useful for converting
+to a `ClampedNumeric` type:
+
+*   `MakeClampedNum()` - Creates a new `ClampedNumeric` from the underlying type
+    of the supplied arithmetic or directly convertible type.
diff --git a/base/numerics/checked_math.h b/base/numerics/checked_math.h
new file mode 100644
index 0000000..ede3344
--- /dev/null
+++ b/base/numerics/checked_math.h
@@ -0,0 +1,393 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_CHECKED_MATH_H_
+#define BASE_NUMERICS_CHECKED_MATH_H_
+
+#include <stddef.h>
+
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/checked_math_impl.h"
+
+namespace base {
+namespace internal {
+
+template <typename T>
+class CheckedNumeric {
+  static_assert(std::is_arithmetic<T>::value,
+                "CheckedNumeric<T>: T must be a numeric type.");
+
+ public:
+  using type = T;
+
+  constexpr CheckedNumeric() = default;
+
+  // Copy constructor.
+  template <typename Src>
+  constexpr CheckedNumeric(const CheckedNumeric<Src>& rhs)
+      : state_(rhs.state_.value(), rhs.IsValid()) {}
+
+  template <typename Src>
+  friend class CheckedNumeric;
+
+  // This is not an explicit constructor because we implicitly upgrade regular
+  // numerics to CheckedNumerics to make them easier to use.
+  template <typename Src>
+  constexpr CheckedNumeric(Src value)  // NOLINT(runtime/explicit)
+      : state_(value) {
+    static_assert(std::is_arithmetic<Src>::value, "Argument must be numeric.");
+  }
+
+  // This is not an explicit constructor because we want a seamless conversion
+  // from StrictNumeric types.
+  template <typename Src>
+  constexpr CheckedNumeric(
+      StrictNumeric<Src> value)  // NOLINT(runtime/explicit)
+      : state_(static_cast<Src>(value)) {}
+
+  // IsValid() - The public API to test if a CheckedNumeric is currently valid.
+  // A range checked destination type can be supplied using the Dst template
+  // parameter.
+  template <typename Dst = T>
+  constexpr bool IsValid() const {
+    return state_.is_valid() &&
+           IsValueInRangeForNumericType<Dst>(state_.value());
+  }
+
+  // AssignIfValid(Dst) - Assigns the underlying value if it is currently valid
+  // and is within the range supported by the destination type. Returns true if
+  // successful and false otherwise.
+  template <typename Dst>
+#if defined(__clang__) || defined(__GNUC__)
+  __attribute__((warn_unused_result))
+#elif defined(_MSC_VER)
+  _Check_return_
+#endif
+  constexpr bool
+  AssignIfValid(Dst* result) const {
+    return BASE_NUMERICS_LIKELY(IsValid<Dst>())
+               ? ((*result = static_cast<Dst>(state_.value())), true)
+               : false;
+  }
+
+  // ValueOrDie() - The primary accessor for the underlying value. If the
+  // current state is not valid it will CHECK and crash.
+  // A range checked destination type can be supplied using the Dst template
+  // parameter, which will trigger a CHECK if the value is not in bounds for
+  // the destination.
+  // The CHECK behavior can be overridden by supplying a handler as a
+  // template parameter, for test code, etc. However, the handler cannot access
+  // the underlying value, and it is not available through other means.
+  template <typename Dst = T, class CheckHandler = CheckOnFailure>
+  constexpr StrictNumeric<Dst> ValueOrDie() const {
+    return BASE_NUMERICS_LIKELY(IsValid<Dst>())
+               ? static_cast<Dst>(state_.value())
+               : CheckHandler::template HandleFailure<Dst>();
+  }
+
+  // ValueOrDefault(T default_value) - A convenience method that returns the
+  // current value if the state is valid, and the supplied default_value for
+  // any other state.
+  // A range checked destination type can be supplied using the Dst template
+  // parameter. WARNING: This function may fail to compile or CHECK at runtime
+  // if the supplied default_value is not within range of the destination type.
+  template <typename Dst = T, typename Src>
+  constexpr StrictNumeric<Dst> ValueOrDefault(const Src default_value) const {
+    return BASE_NUMERICS_LIKELY(IsValid<Dst>())
+               ? static_cast<Dst>(state_.value())
+               : checked_cast<Dst>(default_value);
+  }
+
+  // Returns a checked numeric of the specified type, cast from the current
+  // CheckedNumeric. If the current state is invalid or the destination cannot
+  // represent the result then the returned CheckedNumeric will be invalid.
+  template <typename Dst>
+  constexpr CheckedNumeric<typename UnderlyingType<Dst>::type> Cast() const {
+    return *this;
+  }
+
+  // This friend method is available solely for providing more detailed logging
+  // in the the tests. Do not implement it in production code, because the
+  // underlying values may change at any time.
+  template <typename U>
+  friend U GetNumericValueForTest(const CheckedNumeric<U>& src);
+
+  // Prototypes for the supported arithmetic operator overloads.
+  template <typename Src>
+  constexpr CheckedNumeric& operator+=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator-=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator*=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator/=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator%=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator<<=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator>>=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator&=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator|=(const Src rhs);
+  template <typename Src>
+  constexpr CheckedNumeric& operator^=(const Src rhs);
+
+  constexpr CheckedNumeric operator-() const {
+    // The negation of two's complement int min is int min, so we simply
+    // check for that in the constexpr case.
+    // We use an optimized code path for a known run-time variable.
+    return MustTreatAsConstexpr(state_.value()) || !std::is_signed<T>::value ||
+                   std::is_floating_point<T>::value
+               ? CheckedNumeric<T>(
+                     NegateWrapper(state_.value()),
+                     IsValid() && (!std::is_signed<T>::value ||
+                                   std::is_floating_point<T>::value ||
+                                   NegateWrapper(state_.value()) !=
+                                       std::numeric_limits<T>::lowest()))
+               : FastRuntimeNegate();
+  }
+
+  constexpr CheckedNumeric operator~() const {
+    return CheckedNumeric<decltype(InvertWrapper(T()))>(
+        InvertWrapper(state_.value()), IsValid());
+  }
+
+  constexpr CheckedNumeric Abs() const {
+    return !IsValueNegative(state_.value()) ? *this : -*this;
+  }
+
+  template <typename U>
+  constexpr CheckedNumeric<typename MathWrapper<CheckedMaxOp, T, U>::type> Max(
+      const U rhs) const {
+    using R = typename UnderlyingType<U>::type;
+    using result_type = typename MathWrapper<CheckedMaxOp, T, U>::type;
+    // TODO(jschuh): This can be converted to the MathOp version and remain
+    // constexpr once we have C++14 support.
+    return CheckedNumeric<result_type>(
+        static_cast<result_type>(
+            IsGreater<T, R>::Test(state_.value(), Wrapper<U>::value(rhs))
+                ? state_.value()
+                : Wrapper<U>::value(rhs)),
+        state_.is_valid() && Wrapper<U>::is_valid(rhs));
+  }
+
+  template <typename U>
+  constexpr CheckedNumeric<typename MathWrapper<CheckedMinOp, T, U>::type> Min(
+      const U rhs) const {
+    using R = typename UnderlyingType<U>::type;
+    using result_type = typename MathWrapper<CheckedMinOp, T, U>::type;
+    // TODO(jschuh): This can be converted to the MathOp version and remain
+    // constexpr once we have C++14 support.
+    return CheckedNumeric<result_type>(
+        static_cast<result_type>(
+            IsLess<T, R>::Test(state_.value(), Wrapper<U>::value(rhs))
+                ? state_.value()
+                : Wrapper<U>::value(rhs)),
+        state_.is_valid() && Wrapper<U>::is_valid(rhs));
+  }
+
+  // This function is available only for integral types. It returns an unsigned
+  // integer of the same width as the source type, containing the absolute value
+  // of the source, and properly handling signed min.
+  constexpr CheckedNumeric<typename UnsignedOrFloatForSize<T>::type>
+  UnsignedAbs() const {
+    return CheckedNumeric<typename UnsignedOrFloatForSize<T>::type>(
+        SafeUnsignedAbs(state_.value()), state_.is_valid());
+  }
+
+  constexpr CheckedNumeric& operator++() {
+    *this += 1;
+    return *this;
+  }
+
+  constexpr CheckedNumeric operator++(int) {
+    CheckedNumeric value = *this;
+    *this += 1;
+    return value;
+  }
+
+  constexpr CheckedNumeric& operator--() {
+    *this -= 1;
+    return *this;
+  }
+
+  constexpr CheckedNumeric operator--(int) {
+    CheckedNumeric value = *this;
+    *this -= 1;
+    return value;
+  }
+
+  // These perform the actual math operations on the CheckedNumerics.
+  // Binary arithmetic operations.
+  template <template <typename, typename, typename> class M,
+            typename L,
+            typename R>
+  static constexpr CheckedNumeric MathOp(const L lhs, const R rhs) {
+    using Math = typename MathWrapper<M, L, R>::math;
+    T result = 0;
+    bool is_valid =
+        Wrapper<L>::is_valid(lhs) && Wrapper<R>::is_valid(rhs) &&
+        Math::Do(Wrapper<L>::value(lhs), Wrapper<R>::value(rhs), &result);
+    return CheckedNumeric<T>(result, is_valid);
+  }
+
+  // Assignment arithmetic operations.
+  template <template <typename, typename, typename> class M, typename R>
+  constexpr CheckedNumeric& MathOp(const R rhs) {
+    using Math = typename MathWrapper<M, T, R>::math;
+    T result = 0;  // Using T as the destination saves a range check.
+    bool is_valid = state_.is_valid() && Wrapper<R>::is_valid(rhs) &&
+                    Math::Do(state_.value(), Wrapper<R>::value(rhs), &result);
+    *this = CheckedNumeric<T>(result, is_valid);
+    return *this;
+  }
+
+ private:
+  CheckedNumericState<T> state_;
+
+  CheckedNumeric FastRuntimeNegate() const {
+    T result;
+    bool success = CheckedSubOp<T, T>::Do(T(0), state_.value(), &result);
+    return CheckedNumeric<T>(result, IsValid() && success);
+  }
+
+  template <typename Src>
+  constexpr CheckedNumeric(Src value, bool is_valid)
+      : state_(value, is_valid) {}
+
+  // These wrappers allow us to handle state the same way for both
+  // CheckedNumeric and POD arithmetic types.
+  template <typename Src>
+  struct Wrapper {
+    static constexpr bool is_valid(Src) { return true; }
+    static constexpr Src value(Src value) { return value; }
+  };
+
+  template <typename Src>
+  struct Wrapper<CheckedNumeric<Src>> {
+    static constexpr bool is_valid(const CheckedNumeric<Src> v) {
+      return v.IsValid();
+    }
+    static constexpr Src value(const CheckedNumeric<Src> v) {
+      return v.state_.value();
+    }
+  };
+
+  template <typename Src>
+  struct Wrapper<StrictNumeric<Src>> {
+    static constexpr bool is_valid(const StrictNumeric<Src>) { return true; }
+    static constexpr Src value(const StrictNumeric<Src> v) {
+      return static_cast<Src>(v);
+    }
+  };
+};
+
+// Convenience functions to avoid the ugly template disambiguator syntax.
+template <typename Dst, typename Src>
+constexpr bool IsValidForType(const CheckedNumeric<Src> value) {
+  return value.template IsValid<Dst>();
+}
+
+template <typename Dst, typename Src>
+constexpr StrictNumeric<Dst> ValueOrDieForType(
+    const CheckedNumeric<Src> value) {
+  return value.template ValueOrDie<Dst>();
+}
+
+template <typename Dst, typename Src, typename Default>
+constexpr StrictNumeric<Dst> ValueOrDefaultForType(
+    const CheckedNumeric<Src> value,
+    const Default default_value) {
+  return value.template ValueOrDefault<Dst>(default_value);
+}
+
+// Convience wrapper to return a new CheckedNumeric from the provided arithmetic
+// or CheckedNumericType.
+template <typename T>
+constexpr CheckedNumeric<typename UnderlyingType<T>::type> MakeCheckedNum(
+    const T value) {
+  return value;
+}
+
+// These implement the variadic wrapper for the math operations.
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R>
+constexpr CheckedNumeric<typename MathWrapper<M, L, R>::type> CheckMathOp(
+    const L lhs,
+    const R rhs) {
+  using Math = typename MathWrapper<M, L, R>::math;
+  return CheckedNumeric<typename Math::result_type>::template MathOp<M>(lhs,
+                                                                        rhs);
+}
+
+// General purpose wrapper template for arithmetic operations.
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R,
+          typename... Args>
+constexpr CheckedNumeric<typename ResultType<M, L, R, Args...>::type>
+CheckMathOp(const L lhs, const R rhs, const Args... args) {
+  return CheckMathOp<M>(CheckMathOp<M>(lhs, rhs), args...);
+}
+
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Add, +, +=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Sub, -, -=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Mul, *, *=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Div, /, /=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Mod, %, %=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Lsh, <<, <<=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Rsh, >>, >>=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, And, &, &=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Or, |, |=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Xor, ^, ^=)
+BASE_NUMERIC_ARITHMETIC_VARIADIC(Checked, Check, Max)
+BASE_NUMERIC_ARITHMETIC_VARIADIC(Checked, Check, Min)
+
+// These are some extra StrictNumeric operators to support simple pointer
+// arithmetic with our result types. Since wrapping on a pointer is always
+// bad, we trigger the CHECK condition here.
+template <typename L, typename R>
+L* operator+(L* lhs, const StrictNumeric<R> rhs) {
+  uintptr_t result = CheckAdd(reinterpret_cast<uintptr_t>(lhs),
+                              CheckMul(sizeof(L), static_cast<R>(rhs)))
+                         .template ValueOrDie<uintptr_t>();
+  return reinterpret_cast<L*>(result);
+}
+
+template <typename L, typename R>
+L* operator-(L* lhs, const StrictNumeric<R> rhs) {
+  uintptr_t result = CheckSub(reinterpret_cast<uintptr_t>(lhs),
+                              CheckMul(sizeof(L), static_cast<R>(rhs)))
+                         .template ValueOrDie<uintptr_t>();
+  return reinterpret_cast<L*>(result);
+}
+
+}  // namespace internal
+
+using internal::CheckedNumeric;
+using internal::IsValidForType;
+using internal::ValueOrDieForType;
+using internal::ValueOrDefaultForType;
+using internal::MakeCheckedNum;
+using internal::CheckMax;
+using internal::CheckMin;
+using internal::CheckAdd;
+using internal::CheckSub;
+using internal::CheckMul;
+using internal::CheckDiv;
+using internal::CheckMod;
+using internal::CheckLsh;
+using internal::CheckRsh;
+using internal::CheckAnd;
+using internal::CheckOr;
+using internal::CheckXor;
+
+}  // namespace base
+
+#endif  // BASE_NUMERICS_CHECKED_MATH_H_
diff --git a/base/numerics/checked_math_impl.h b/base/numerics/checked_math_impl.h
new file mode 100644
index 0000000..e083389
--- /dev/null
+++ b/base/numerics/checked_math_impl.h
@@ -0,0 +1,567 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_CHECKED_MATH_IMPL_H_
+#define BASE_NUMERICS_CHECKED_MATH_IMPL_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <climits>
+#include <cmath>
+#include <cstdlib>
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/safe_conversions.h"
+#include "base/numerics/safe_math_shared_impl.h"
+
+namespace base {
+namespace internal {
+
+template <typename T>
+constexpr bool CheckedAddImpl(T x, T y, T* result) {
+  static_assert(std::is_integral<T>::value, "Type must be integral");
+  // Since the value of x+y is undefined if we have a signed type, we compute
+  // it using the unsigned type of the same size.
+  using UnsignedDst = typename std::make_unsigned<T>::type;
+  using SignedDst = typename std::make_signed<T>::type;
+  UnsignedDst ux = static_cast<UnsignedDst>(x);
+  UnsignedDst uy = static_cast<UnsignedDst>(y);
+  UnsignedDst uresult = static_cast<UnsignedDst>(ux + uy);
+  *result = static_cast<T>(uresult);
+  // Addition is valid if the sign of (x + y) is equal to either that of x or
+  // that of y.
+  return (std::is_signed<T>::value)
+             ? static_cast<SignedDst>((uresult ^ ux) & (uresult ^ uy)) >= 0
+             : uresult >= uy;  // Unsigned is either valid or underflow.
+}
+
+template <typename T, typename U, class Enable = void>
+struct CheckedAddOp {};
+
+template <typename T, typename U>
+struct CheckedAddOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    // TODO(jschuh) Make this "constexpr if" once we're C++17.
+    if (CheckedAddFastOp<T, U>::is_supported)
+      return CheckedAddFastOp<T, U>::Do(x, y, result);
+
+    // Double the underlying type up to a full machine word.
+    using FastPromotion = typename FastIntegerArithmeticPromotion<T, U>::type;
+    using Promotion =
+        typename std::conditional<(IntegerBitsPlusSign<FastPromotion>::value >
+                                   IntegerBitsPlusSign<intptr_t>::value),
+                                  typename BigEnoughPromotion<T, U>::type,
+                                  FastPromotion>::type;
+    // Fail if either operand is out of range for the promoted type.
+    // TODO(jschuh): This could be made to work for a broader range of values.
+    if (BASE_NUMERICS_UNLIKELY(!IsValueInRangeForNumericType<Promotion>(x) ||
+                               !IsValueInRangeForNumericType<Promotion>(y))) {
+      return false;
+    }
+
+    Promotion presult = {};
+    bool is_valid = true;
+    if (IsIntegerArithmeticSafe<Promotion, T, U>::value) {
+      presult = static_cast<Promotion>(x) + static_cast<Promotion>(y);
+    } else {
+      is_valid = CheckedAddImpl(static_cast<Promotion>(x),
+                                static_cast<Promotion>(y), &presult);
+    }
+    *result = static_cast<V>(presult);
+    return is_valid && IsValueInRangeForNumericType<V>(presult);
+  }
+};
+
+template <typename T>
+constexpr bool CheckedSubImpl(T x, T y, T* result) {
+  static_assert(std::is_integral<T>::value, "Type must be integral");
+  // Since the value of x+y is undefined if we have a signed type, we compute
+  // it using the unsigned type of the same size.
+  using UnsignedDst = typename std::make_unsigned<T>::type;
+  using SignedDst = typename std::make_signed<T>::type;
+  UnsignedDst ux = static_cast<UnsignedDst>(x);
+  UnsignedDst uy = static_cast<UnsignedDst>(y);
+  UnsignedDst uresult = static_cast<UnsignedDst>(ux - uy);
+  *result = static_cast<T>(uresult);
+  // Subtraction is valid if either x and y have same sign, or (x-y) and x have
+  // the same sign.
+  return (std::is_signed<T>::value)
+             ? static_cast<SignedDst>((uresult ^ ux) & (ux ^ uy)) >= 0
+             : x >= y;
+}
+
+template <typename T, typename U, class Enable = void>
+struct CheckedSubOp {};
+
+template <typename T, typename U>
+struct CheckedSubOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    // TODO(jschuh) Make this "constexpr if" once we're C++17.
+    if (CheckedSubFastOp<T, U>::is_supported)
+      return CheckedSubFastOp<T, U>::Do(x, y, result);
+
+    // Double the underlying type up to a full machine word.
+    using FastPromotion = typename FastIntegerArithmeticPromotion<T, U>::type;
+    using Promotion =
+        typename std::conditional<(IntegerBitsPlusSign<FastPromotion>::value >
+                                   IntegerBitsPlusSign<intptr_t>::value),
+                                  typename BigEnoughPromotion<T, U>::type,
+                                  FastPromotion>::type;
+    // Fail if either operand is out of range for the promoted type.
+    // TODO(jschuh): This could be made to work for a broader range of values.
+    if (BASE_NUMERICS_UNLIKELY(!IsValueInRangeForNumericType<Promotion>(x) ||
+                               !IsValueInRangeForNumericType<Promotion>(y))) {
+      return false;
+    }
+
+    Promotion presult = {};
+    bool is_valid = true;
+    if (IsIntegerArithmeticSafe<Promotion, T, U>::value) {
+      presult = static_cast<Promotion>(x) - static_cast<Promotion>(y);
+    } else {
+      is_valid = CheckedSubImpl(static_cast<Promotion>(x),
+                                static_cast<Promotion>(y), &presult);
+    }
+    *result = static_cast<V>(presult);
+    return is_valid && IsValueInRangeForNumericType<V>(presult);
+  }
+};
+
+template <typename T>
+constexpr bool CheckedMulImpl(T x, T y, T* result) {
+  static_assert(std::is_integral<T>::value, "Type must be integral");
+  // Since the value of x*y is potentially undefined if we have a signed type,
+  // we compute it using the unsigned type of the same size.
+  using UnsignedDst = typename std::make_unsigned<T>::type;
+  using SignedDst = typename std::make_signed<T>::type;
+  const UnsignedDst ux = SafeUnsignedAbs(x);
+  const UnsignedDst uy = SafeUnsignedAbs(y);
+  UnsignedDst uresult = static_cast<UnsignedDst>(ux * uy);
+  const bool is_negative =
+      std::is_signed<T>::value && static_cast<SignedDst>(x ^ y) < 0;
+  *result = is_negative ? 0 - uresult : uresult;
+  // We have a fast out for unsigned identity or zero on the second operand.
+  // After that it's an unsigned overflow check on the absolute value, with
+  // a +1 bound for a negative result.
+  return uy <= UnsignedDst(!std::is_signed<T>::value || is_negative) ||
+         ux <= (std::numeric_limits<T>::max() + UnsignedDst(is_negative)) / uy;
+}
+
+template <typename T, typename U, class Enable = void>
+struct CheckedMulOp {};
+
+template <typename T, typename U>
+struct CheckedMulOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    // TODO(jschuh) Make this "constexpr if" once we're C++17.
+    if (CheckedMulFastOp<T, U>::is_supported)
+      return CheckedMulFastOp<T, U>::Do(x, y, result);
+
+    using Promotion = typename FastIntegerArithmeticPromotion<T, U>::type;
+    // Verify the destination type can hold the result (always true for 0).
+    if (BASE_NUMERICS_UNLIKELY((!IsValueInRangeForNumericType<Promotion>(x) ||
+                                !IsValueInRangeForNumericType<Promotion>(y)) &&
+                               x && y)) {
+      return false;
+    }
+
+    Promotion presult = {};
+    bool is_valid = true;
+    if (CheckedMulFastOp<Promotion, Promotion>::is_supported) {
+      // The fast op may be available with the promoted type.
+      is_valid = CheckedMulFastOp<Promotion, Promotion>::Do(x, y, &presult);
+    } else if (IsIntegerArithmeticSafe<Promotion, T, U>::value) {
+      presult = static_cast<Promotion>(x) * static_cast<Promotion>(y);
+    } else {
+      is_valid = CheckedMulImpl(static_cast<Promotion>(x),
+                                static_cast<Promotion>(y), &presult);
+    }
+    *result = static_cast<V>(presult);
+    return is_valid && IsValueInRangeForNumericType<V>(presult);
+  }
+};
+
+// Division just requires a check for a zero denominator or an invalid negation
+// on signed min/-1.
+template <typename T, typename U, class Enable = void>
+struct CheckedDivOp {};
+
+template <typename T, typename U>
+struct CheckedDivOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    if (BASE_NUMERICS_UNLIKELY(!y))
+      return false;
+
+    // The overflow check can be compiled away if we don't have the exact
+    // combination of types needed to trigger this case.
+    using Promotion = typename BigEnoughPromotion<T, U>::type;
+    if (BASE_NUMERICS_UNLIKELY(
+            (std::is_signed<T>::value && std::is_signed<U>::value &&
+             IsTypeInRangeForNumericType<T, Promotion>::value &&
+             static_cast<Promotion>(x) ==
+                 std::numeric_limits<Promotion>::lowest() &&
+             y == static_cast<U>(-1)))) {
+      return false;
+    }
+
+    // This branch always compiles away if the above branch wasn't removed.
+    if (BASE_NUMERICS_UNLIKELY((!IsValueInRangeForNumericType<Promotion>(x) ||
+                                !IsValueInRangeForNumericType<Promotion>(y)) &&
+                               x)) {
+      return false;
+    }
+
+    Promotion presult = Promotion(x) / Promotion(y);
+    *result = static_cast<V>(presult);
+    return IsValueInRangeForNumericType<V>(presult);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct CheckedModOp {};
+
+template <typename T, typename U>
+struct CheckedModOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    using Promotion = typename BigEnoughPromotion<T, U>::type;
+    if (BASE_NUMERICS_LIKELY(y)) {
+      Promotion presult = static_cast<Promotion>(x) % static_cast<Promotion>(y);
+      *result = static_cast<Promotion>(presult);
+      return IsValueInRangeForNumericType<V>(presult);
+    }
+    return false;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct CheckedLshOp {};
+
+// Left shift. Shifts less than 0 or greater than or equal to the number
+// of bits in the promoted type are undefined. Shifts of negative values
+// are undefined. Otherwise it is defined when the result fits.
+template <typename T, typename U>
+struct CheckedLshOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = T;
+  template <typename V>
+  static constexpr bool Do(T x, U shift, V* result) {
+    // Disallow negative numbers and verify the shift is in bounds.
+    if (BASE_NUMERICS_LIKELY(!IsValueNegative(x) &&
+                             as_unsigned(shift) <
+                                 as_unsigned(std::numeric_limits<T>::digits))) {
+      // Shift as unsigned to avoid undefined behavior.
+      *result = static_cast<V>(as_unsigned(x) << shift);
+      // If the shift can be reversed, we know it was valid.
+      return *result >> shift == x;
+    }
+
+    // Handle the legal corner-case of a full-width signed shift of zero.
+    return std::is_signed<T>::value && !x &&
+           as_unsigned(shift) == as_unsigned(std::numeric_limits<T>::digits);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct CheckedRshOp {};
+
+// Right shift. Shifts less than 0 or greater than or equal to the number
+// of bits in the promoted type are undefined. Otherwise, it is always defined,
+// but a right shift of a negative value is implementation-dependent.
+template <typename T, typename U>
+struct CheckedRshOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = T;
+  template <typename V>
+  static bool Do(T x, U shift, V* result) {
+    // Use the type conversion push negative values out of range.
+    if (BASE_NUMERICS_LIKELY(as_unsigned(shift) <
+                             IntegerBitsPlusSign<T>::value)) {
+      T tmp = x >> shift;
+      *result = static_cast<V>(tmp);
+      return IsValueInRangeForNumericType<V>(tmp);
+    }
+    return false;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct CheckedAndOp {};
+
+// For simplicity we support only unsigned integer results.
+template <typename T, typename U>
+struct CheckedAndOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename std::make_unsigned<
+      typename MaxExponentPromotion<T, U>::type>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    result_type tmp = static_cast<result_type>(x) & static_cast<result_type>(y);
+    *result = static_cast<V>(tmp);
+    return IsValueInRangeForNumericType<V>(tmp);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct CheckedOrOp {};
+
+// For simplicity we support only unsigned integers.
+template <typename T, typename U>
+struct CheckedOrOp<T,
+                   U,
+                   typename std::enable_if<std::is_integral<T>::value &&
+                                           std::is_integral<U>::value>::type> {
+  using result_type = typename std::make_unsigned<
+      typename MaxExponentPromotion<T, U>::type>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    result_type tmp = static_cast<result_type>(x) | static_cast<result_type>(y);
+    *result = static_cast<V>(tmp);
+    return IsValueInRangeForNumericType<V>(tmp);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct CheckedXorOp {};
+
+// For simplicity we support only unsigned integers.
+template <typename T, typename U>
+struct CheckedXorOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename std::make_unsigned<
+      typename MaxExponentPromotion<T, U>::type>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    result_type tmp = static_cast<result_type>(x) ^ static_cast<result_type>(y);
+    *result = static_cast<V>(tmp);
+    return IsValueInRangeForNumericType<V>(tmp);
+  }
+};
+
+// Max doesn't really need to be implemented this way because it can't fail,
+// but it makes the code much cleaner to use the MathOp wrappers.
+template <typename T, typename U, class Enable = void>
+struct CheckedMaxOp {};
+
+template <typename T, typename U>
+struct CheckedMaxOp<
+    T,
+    U,
+    typename std::enable_if<std::is_arithmetic<T>::value &&
+                            std::is_arithmetic<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    result_type tmp = IsGreater<T, U>::Test(x, y) ? static_cast<result_type>(x)
+                                                  : static_cast<result_type>(y);
+    *result = static_cast<V>(tmp);
+    return IsValueInRangeForNumericType<V>(tmp);
+  }
+};
+
+// Min doesn't really need to be implemented this way because it can't fail,
+// but it makes the code much cleaner to use the MathOp wrappers.
+template <typename T, typename U, class Enable = void>
+struct CheckedMinOp {};
+
+template <typename T, typename U>
+struct CheckedMinOp<
+    T,
+    U,
+    typename std::enable_if<std::is_arithmetic<T>::value &&
+                            std::is_arithmetic<U>::value>::type> {
+  using result_type = typename LowestValuePromotion<T, U>::type;
+  template <typename V>
+  static constexpr bool Do(T x, U y, V* result) {
+    result_type tmp = IsLess<T, U>::Test(x, y) ? static_cast<result_type>(x)
+                                               : static_cast<result_type>(y);
+    *result = static_cast<V>(tmp);
+    return IsValueInRangeForNumericType<V>(tmp);
+  }
+};
+
+// This is just boilerplate that wraps the standard floating point arithmetic.
+// A macro isn't the nicest solution, but it beats rewriting these repeatedly.
+#define BASE_FLOAT_ARITHMETIC_OPS(NAME, OP)                              \
+  template <typename T, typename U>                                      \
+  struct Checked##NAME##Op<                                              \
+      T, U,                                                              \
+      typename std::enable_if<std::is_floating_point<T>::value ||        \
+                              std::is_floating_point<U>::value>::type> { \
+    using result_type = typename MaxExponentPromotion<T, U>::type;       \
+    template <typename V>                                                \
+    static constexpr bool Do(T x, U y, V* result) {                      \
+      using Promotion = typename MaxExponentPromotion<T, U>::type;       \
+      Promotion presult = x OP y;                                        \
+      *result = static_cast<V>(presult);                                 \
+      return IsValueInRangeForNumericType<V>(presult);                   \
+    }                                                                    \
+  };
+
+BASE_FLOAT_ARITHMETIC_OPS(Add, +)
+BASE_FLOAT_ARITHMETIC_OPS(Sub, -)
+BASE_FLOAT_ARITHMETIC_OPS(Mul, *)
+BASE_FLOAT_ARITHMETIC_OPS(Div, /)
+
+#undef BASE_FLOAT_ARITHMETIC_OPS
+
+// Floats carry around their validity state with them, but integers do not. So,
+// we wrap the underlying value in a specialization in order to hide that detail
+// and expose an interface via accessors.
+enum NumericRepresentation {
+  NUMERIC_INTEGER,
+  NUMERIC_FLOATING,
+  NUMERIC_UNKNOWN
+};
+
+template <typename NumericType>
+struct GetNumericRepresentation {
+  static const NumericRepresentation value =
+      std::is_integral<NumericType>::value
+          ? NUMERIC_INTEGER
+          : (std::is_floating_point<NumericType>::value ? NUMERIC_FLOATING
+                                                        : NUMERIC_UNKNOWN);
+};
+
+template <typename T,
+          NumericRepresentation type = GetNumericRepresentation<T>::value>
+class CheckedNumericState {};
+
+// Integrals require quite a bit of additional housekeeping to manage state.
+template <typename T>
+class CheckedNumericState<T, NUMERIC_INTEGER> {
+ private:
+  // is_valid_ precedes value_ because member intializers in the constructors
+  // are evaluated in field order, and is_valid_ must be read when initializing
+  // value_.
+  bool is_valid_;
+  T value_;
+
+  // Ensures that a type conversion does not trigger undefined behavior.
+  template <typename Src>
+  static constexpr T WellDefinedConversionOrZero(const Src value,
+                                                 const bool is_valid) {
+    using SrcType = typename internal::UnderlyingType<Src>::type;
+    return (std::is_integral<SrcType>::value || is_valid)
+               ? static_cast<T>(value)
+               : static_cast<T>(0);
+  }
+
+ public:
+  template <typename Src, NumericRepresentation type>
+  friend class CheckedNumericState;
+
+  constexpr CheckedNumericState() : is_valid_(true), value_(0) {}
+
+  template <typename Src>
+  constexpr CheckedNumericState(Src value, bool is_valid)
+      : is_valid_(is_valid && IsValueInRangeForNumericType<T>(value)),
+        value_(WellDefinedConversionOrZero(value, is_valid_)) {
+    static_assert(std::is_arithmetic<Src>::value, "Argument must be numeric.");
+  }
+
+  // Copy constructor.
+  template <typename Src>
+  constexpr CheckedNumericState(const CheckedNumericState<Src>& rhs)
+      : is_valid_(rhs.IsValid()),
+        value_(WellDefinedConversionOrZero(rhs.value(), is_valid_)) {}
+
+  template <typename Src>
+  constexpr explicit CheckedNumericState(Src value)
+      : is_valid_(IsValueInRangeForNumericType<T>(value)),
+        value_(WellDefinedConversionOrZero(value, is_valid_)) {}
+
+  constexpr bool is_valid() const { return is_valid_; }
+  constexpr T value() const { return value_; }
+};
+
+// Floating points maintain their own validity, but need translation wrappers.
+template <typename T>
+class CheckedNumericState<T, NUMERIC_FLOATING> {
+ private:
+  T value_;
+
+  // Ensures that a type conversion does not trigger undefined behavior.
+  template <typename Src>
+  static constexpr T WellDefinedConversionOrNaN(const Src value,
+                                                const bool is_valid) {
+    using SrcType = typename internal::UnderlyingType<Src>::type;
+    return (StaticDstRangeRelationToSrcRange<T, SrcType>::value ==
+                NUMERIC_RANGE_CONTAINED ||
+            is_valid)
+               ? static_cast<T>(value)
+               : std::numeric_limits<T>::quiet_NaN();
+  }
+
+ public:
+  template <typename Src, NumericRepresentation type>
+  friend class CheckedNumericState;
+
+  constexpr CheckedNumericState() : value_(0.0) {}
+
+  template <typename Src>
+  constexpr CheckedNumericState(Src value, bool is_valid)
+      : value_(WellDefinedConversionOrNaN(value, is_valid)) {}
+
+  template <typename Src>
+  constexpr explicit CheckedNumericState(Src value)
+      : value_(WellDefinedConversionOrNaN(
+            value,
+            IsValueInRangeForNumericType<T>(value))) {}
+
+  // Copy constructor.
+  template <typename Src>
+  constexpr CheckedNumericState(const CheckedNumericState<Src>& rhs)
+      : value_(WellDefinedConversionOrNaN(
+            rhs.value(),
+            rhs.is_valid() && IsValueInRangeForNumericType<T>(rhs.value()))) {}
+
+  constexpr bool is_valid() const {
+    // Written this way because std::isfinite is not reliably constexpr.
+    return MustTreatAsConstexpr(value_)
+               ? value_ <= std::numeric_limits<T>::max() &&
+                     value_ >= std::numeric_limits<T>::lowest()
+               : std::isfinite(value_);
+  }
+  constexpr T value() const { return value_; }
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_NUMERICS_CHECKED_MATH_IMPL_H_
diff --git a/base/numerics/clamped_math.h b/base/numerics/clamped_math.h
new file mode 100644
index 0000000..b184363
--- /dev/null
+++ b/base/numerics/clamped_math.h
@@ -0,0 +1,262 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_CLAMPED_MATH_H_
+#define BASE_NUMERICS_CLAMPED_MATH_H_
+
+#include <stddef.h>
+
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/clamped_math_impl.h"
+
+namespace base {
+namespace internal {
+
+template <typename T>
+class ClampedNumeric {
+  static_assert(std::is_arithmetic<T>::value,
+                "ClampedNumeric<T>: T must be a numeric type.");
+
+ public:
+  using type = T;
+
+  constexpr ClampedNumeric() : value_(0) {}
+
+  // Copy constructor.
+  template <typename Src>
+  constexpr ClampedNumeric(const ClampedNumeric<Src>& rhs)
+      : value_(saturated_cast<T>(rhs.value_)) {}
+
+  template <typename Src>
+  friend class ClampedNumeric;
+
+  // This is not an explicit constructor because we implicitly upgrade regular
+  // numerics to ClampedNumerics to make them easier to use.
+  template <typename Src>
+  constexpr ClampedNumeric(Src value)  // NOLINT(runtime/explicit)
+      : value_(saturated_cast<T>(value)) {
+    static_assert(std::is_arithmetic<Src>::value, "Argument must be numeric.");
+  }
+
+  // This is not an explicit constructor because we want a seamless conversion
+  // from StrictNumeric types.
+  template <typename Src>
+  constexpr ClampedNumeric(
+      StrictNumeric<Src> value)  // NOLINT(runtime/explicit)
+      : value_(saturated_cast<T>(static_cast<Src>(value))) {}
+
+  // Returns a ClampedNumeric of the specified type, cast from the current
+  // ClampedNumeric, and saturated to the destination type.
+  template <typename Dst>
+  constexpr ClampedNumeric<typename UnderlyingType<Dst>::type> Cast() const {
+    return *this;
+  }
+
+  // Prototypes for the supported arithmetic operator overloads.
+  template <typename Src>
+  constexpr ClampedNumeric& operator+=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator-=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator*=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator/=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator%=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator<<=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator>>=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator&=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator|=(const Src rhs);
+  template <typename Src>
+  constexpr ClampedNumeric& operator^=(const Src rhs);
+
+  constexpr ClampedNumeric operator-() const {
+    // The negation of two's complement int min is int min, so that's the
+    // only overflow case where we will saturate.
+    return ClampedNumeric<T>(SaturatedNegWrapper(value_));
+  }
+
+  constexpr ClampedNumeric operator~() const {
+    return ClampedNumeric<decltype(InvertWrapper(T()))>(InvertWrapper(value_));
+  }
+
+  constexpr ClampedNumeric Abs() const {
+    // The negation of two's complement int min is int min, so that's the
+    // only overflow case where we will saturate.
+    return ClampedNumeric<T>(SaturatedAbsWrapper(value_));
+  }
+
+  template <typename U>
+  constexpr ClampedNumeric<typename MathWrapper<ClampedMaxOp, T, U>::type> Max(
+      const U rhs) const {
+    using result_type = typename MathWrapper<ClampedMaxOp, T, U>::type;
+    return ClampedNumeric<result_type>(
+        ClampedMaxOp<T, U>::Do(value_, Wrapper<U>::value(rhs)));
+  }
+
+  template <typename U>
+  constexpr ClampedNumeric<typename MathWrapper<ClampedMinOp, T, U>::type> Min(
+      const U rhs) const {
+    using result_type = typename MathWrapper<ClampedMinOp, T, U>::type;
+    return ClampedNumeric<result_type>(
+        ClampedMinOp<T, U>::Do(value_, Wrapper<U>::value(rhs)));
+  }
+
+  // This function is available only for integral types. It returns an unsigned
+  // integer of the same width as the source type, containing the absolute value
+  // of the source, and properly handling signed min.
+  constexpr ClampedNumeric<typename UnsignedOrFloatForSize<T>::type>
+  UnsignedAbs() const {
+    return ClampedNumeric<typename UnsignedOrFloatForSize<T>::type>(
+        SafeUnsignedAbs(value_));
+  }
+
+  constexpr ClampedNumeric& operator++() {
+    *this += 1;
+    return *this;
+  }
+
+  constexpr ClampedNumeric operator++(int) {
+    ClampedNumeric value = *this;
+    *this += 1;
+    return value;
+  }
+
+  constexpr ClampedNumeric& operator--() {
+    *this -= 1;
+    return *this;
+  }
+
+  constexpr ClampedNumeric operator--(int) {
+    ClampedNumeric value = *this;
+    *this -= 1;
+    return value;
+  }
+
+  // These perform the actual math operations on the ClampedNumerics.
+  // Binary arithmetic operations.
+  template <template <typename, typename, typename> class M,
+            typename L,
+            typename R>
+  static constexpr ClampedNumeric MathOp(const L lhs, const R rhs) {
+    using Math = typename MathWrapper<M, L, R>::math;
+    return ClampedNumeric<T>(
+        Math::template Do<T>(Wrapper<L>::value(lhs), Wrapper<R>::value(rhs)));
+  }
+
+  // Assignment arithmetic operations.
+  template <template <typename, typename, typename> class M, typename R>
+  constexpr ClampedNumeric& MathOp(const R rhs) {
+    using Math = typename MathWrapper<M, T, R>::math;
+    *this =
+        ClampedNumeric<T>(Math::template Do<T>(value_, Wrapper<R>::value(rhs)));
+    return *this;
+  }
+
+  template <typename Dst>
+  constexpr operator Dst() const {
+    return saturated_cast<typename ArithmeticOrUnderlyingEnum<Dst>::type>(
+        value_);
+  }
+
+  // This method extracts the raw integer value without saturating it to the
+  // destination type as the conversion operator does. This is useful when
+  // e.g. assigning to an auto type or passing as a deduced template parameter.
+  constexpr T RawValue() const { return value_; }
+
+ private:
+  T value_;
+
+  // These wrappers allow us to handle state the same way for both
+  // ClampedNumeric and POD arithmetic types.
+  template <typename Src>
+  struct Wrapper {
+    static constexpr Src value(Src value) {
+      return static_cast<typename UnderlyingType<Src>::type>(value);
+    }
+  };
+};
+
+// Convience wrapper to return a new ClampedNumeric from the provided arithmetic
+// or ClampedNumericType.
+template <typename T>
+constexpr ClampedNumeric<typename UnderlyingType<T>::type> MakeClampedNum(
+    const T value) {
+  return value;
+}
+
+// Overload the ostream output operator to make logging work nicely.
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const ClampedNumeric<T>& value) {
+  os << static_cast<T>(value);
+  return os;
+}
+
+// These implement the variadic wrapper for the math operations.
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R>
+constexpr ClampedNumeric<typename MathWrapper<M, L, R>::type> ClampMathOp(
+    const L lhs,
+    const R rhs) {
+  using Math = typename MathWrapper<M, L, R>::math;
+  return ClampedNumeric<typename Math::result_type>::template MathOp<M>(lhs,
+                                                                        rhs);
+}
+
+// General purpose wrapper template for arithmetic operations.
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R,
+          typename... Args>
+constexpr ClampedNumeric<typename ResultType<M, L, R, Args...>::type>
+ClampMathOp(const L lhs, const R rhs, const Args... args) {
+  return ClampMathOp<M>(ClampMathOp<M>(lhs, rhs), args...);
+}
+
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Add, +, +=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Sub, -, -=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Mul, *, *=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Div, /, /=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Mod, %, %=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Lsh, <<, <<=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Rsh, >>, >>=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, And, &, &=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Or, |, |=)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Xor, ^, ^=)
+BASE_NUMERIC_ARITHMETIC_VARIADIC(Clamped, Clamp, Max)
+BASE_NUMERIC_ARITHMETIC_VARIADIC(Clamped, Clamp, Min)
+BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsLess, <);
+BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsLessOrEqual, <=);
+BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsGreater, >);
+BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsGreaterOrEqual, >=);
+BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsEqual, ==);
+BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsNotEqual, !=);
+
+}  // namespace internal
+
+using internal::ClampedNumeric;
+using internal::MakeClampedNum;
+using internal::ClampMax;
+using internal::ClampMin;
+using internal::ClampAdd;
+using internal::ClampSub;
+using internal::ClampMul;
+using internal::ClampDiv;
+using internal::ClampMod;
+using internal::ClampLsh;
+using internal::ClampRsh;
+using internal::ClampAnd;
+using internal::ClampOr;
+using internal::ClampXor;
+
+}  // namespace base
+
+#endif  // BASE_NUMERICS_CLAMPED_MATH_H_
diff --git a/base/numerics/clamped_math_impl.h b/base/numerics/clamped_math_impl.h
new file mode 100644
index 0000000..303a7e9
--- /dev/null
+++ b/base/numerics/clamped_math_impl.h
@@ -0,0 +1,341 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_CLAMPED_MATH_IMPL_H_
+#define BASE_NUMERICS_CLAMPED_MATH_IMPL_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <climits>
+#include <cmath>
+#include <cstdlib>
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/checked_math.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/numerics/safe_math_shared_impl.h"
+
+namespace base {
+namespace internal {
+
+template <typename T,
+          typename std::enable_if<std::is_integral<T>::value &&
+                                  std::is_signed<T>::value>::type* = nullptr>
+constexpr T SaturatedNegWrapper(T value) {
+  return MustTreatAsConstexpr(value) || !ClampedNegFastOp<T>::is_supported
+             ? (NegateWrapper(value) != std::numeric_limits<T>::lowest()
+                    ? NegateWrapper(value)
+                    : std::numeric_limits<T>::max())
+             : ClampedNegFastOp<T>::Do(value);
+}
+
+template <typename T,
+          typename std::enable_if<std::is_integral<T>::value &&
+                                  !std::is_signed<T>::value>::type* = nullptr>
+constexpr T SaturatedNegWrapper(T value) {
+  return T(0);
+}
+
+template <
+    typename T,
+    typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr>
+constexpr T SaturatedNegWrapper(T value) {
+  return -value;
+}
+
+template <typename T,
+          typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
+constexpr T SaturatedAbsWrapper(T value) {
+  // The calculation below is a static identity for unsigned types, but for
+  // signed integer types it provides a non-branching, saturated absolute value.
+  // This works because SafeUnsignedAbs() returns an unsigned type, which can
+  // represent the absolute value of all negative numbers of an equal-width
+  // integer type. The call to IsValueNegative() then detects overflow in the
+  // special case of numeric_limits<T>::min(), by evaluating the bit pattern as
+  // a signed integer value. If it is the overflow case, we end up subtracting
+  // one from the unsigned result, thus saturating to numeric_limits<T>::max().
+  return static_cast<T>(SafeUnsignedAbs(value) -
+                        IsValueNegative<T>(SafeUnsignedAbs(value)));
+}
+
+template <
+    typename T,
+    typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr>
+constexpr T SaturatedAbsWrapper(T value) {
+  return value < 0 ? -value : value;
+}
+
+template <typename T, typename U, class Enable = void>
+struct ClampedAddOp {};
+
+template <typename T, typename U>
+struct ClampedAddOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U y) {
+    if (ClampedAddFastOp<T, U>::is_supported)
+      return ClampedAddFastOp<T, U>::template Do<V>(x, y);
+
+    static_assert(std::is_same<V, result_type>::value ||
+                      IsTypeInRangeForNumericType<U, V>::value,
+                  "The saturation result cannot be determined from the "
+                  "provided types.");
+    const V saturated = CommonMaxOrMin<V>(IsValueNegative(y));
+    V result = {};
+    return BASE_NUMERICS_LIKELY((CheckedAddOp<T, U>::Do(x, y, &result)))
+               ? result
+               : saturated;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedSubOp {};
+
+template <typename T, typename U>
+struct ClampedSubOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U y) {
+    // TODO(jschuh) Make this "constexpr if" once we're C++17.
+    if (ClampedSubFastOp<T, U>::is_supported)
+      return ClampedSubFastOp<T, U>::template Do<V>(x, y);
+
+    static_assert(std::is_same<V, result_type>::value ||
+                      IsTypeInRangeForNumericType<U, V>::value,
+                  "The saturation result cannot be determined from the "
+                  "provided types.");
+    const V saturated = CommonMaxOrMin<V>(!IsValueNegative(y));
+    V result = {};
+    return BASE_NUMERICS_LIKELY((CheckedSubOp<T, U>::Do(x, y, &result)))
+               ? result
+               : saturated;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedMulOp {};
+
+template <typename T, typename U>
+struct ClampedMulOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U y) {
+    // TODO(jschuh) Make this "constexpr if" once we're C++17.
+    if (ClampedMulFastOp<T, U>::is_supported)
+      return ClampedMulFastOp<T, U>::template Do<V>(x, y);
+
+    V result = {};
+    const V saturated =
+        CommonMaxOrMin<V>(IsValueNegative(x) ^ IsValueNegative(y));
+    return BASE_NUMERICS_LIKELY((CheckedMulOp<T, U>::Do(x, y, &result)))
+               ? result
+               : saturated;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedDivOp {};
+
+template <typename T, typename U>
+struct ClampedDivOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U y) {
+    V result = {};
+    if (BASE_NUMERICS_LIKELY((CheckedDivOp<T, U>::Do(x, y, &result))))
+      return result;
+    // Saturation goes to max, min, or NaN (if x is zero).
+    return x ? CommonMaxOrMin<V>(IsValueNegative(x) ^ IsValueNegative(y))
+             : SaturationDefaultLimits<V>::NaN();
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedModOp {};
+
+template <typename T, typename U>
+struct ClampedModOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U y) {
+    V result = {};
+    return BASE_NUMERICS_LIKELY((CheckedModOp<T, U>::Do(x, y, &result)))
+               ? result
+               : x;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedLshOp {};
+
+// Left shift. Non-zero values saturate in the direction of the sign. A zero
+// shifted by any value always results in zero.
+template <typename T, typename U>
+struct ClampedLshOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = T;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U shift) {
+    static_assert(!std::is_signed<U>::value, "Shift value must be unsigned.");
+    if (BASE_NUMERICS_LIKELY(shift < std::numeric_limits<T>::digits)) {
+      // Shift as unsigned to avoid undefined behavior.
+      V result = static_cast<V>(as_unsigned(x) << shift);
+      // If the shift can be reversed, we know it was valid.
+      if (BASE_NUMERICS_LIKELY(result >> shift == x))
+        return result;
+    }
+    return x ? CommonMaxOrMin<V>(IsValueNegative(x)) : 0;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedRshOp {};
+
+// Right shift. Negative values saturate to -1. Positive or 0 saturates to 0.
+template <typename T, typename U>
+struct ClampedRshOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = T;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U shift) {
+    static_assert(!std::is_signed<U>::value, "Shift value must be unsigned.");
+    // Signed right shift is odd, because it saturates to -1 or 0.
+    const V saturated = as_unsigned(V(0)) - IsValueNegative(x);
+    return BASE_NUMERICS_LIKELY(shift < IntegerBitsPlusSign<T>::value)
+               ? saturated_cast<V>(x >> shift)
+               : saturated;
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedAndOp {};
+
+template <typename T, typename U>
+struct ClampedAndOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename std::make_unsigned<
+      typename MaxExponentPromotion<T, U>::type>::type;
+  template <typename V>
+  static constexpr V Do(T x, U y) {
+    return static_cast<result_type>(x) & static_cast<result_type>(y);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedOrOp {};
+
+// For simplicity we promote to unsigned integers.
+template <typename T, typename U>
+struct ClampedOrOp<T,
+                   U,
+                   typename std::enable_if<std::is_integral<T>::value &&
+                                           std::is_integral<U>::value>::type> {
+  using result_type = typename std::make_unsigned<
+      typename MaxExponentPromotion<T, U>::type>::type;
+  template <typename V>
+  static constexpr V Do(T x, U y) {
+    return static_cast<result_type>(x) | static_cast<result_type>(y);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedXorOp {};
+
+// For simplicity we support only unsigned integers.
+template <typename T, typename U>
+struct ClampedXorOp<T,
+                    U,
+                    typename std::enable_if<std::is_integral<T>::value &&
+                                            std::is_integral<U>::value>::type> {
+  using result_type = typename std::make_unsigned<
+      typename MaxExponentPromotion<T, U>::type>::type;
+  template <typename V>
+  static constexpr V Do(T x, U y) {
+    return static_cast<result_type>(x) ^ static_cast<result_type>(y);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedMaxOp {};
+
+template <typename T, typename U>
+struct ClampedMaxOp<
+    T,
+    U,
+    typename std::enable_if<std::is_arithmetic<T>::value &&
+                            std::is_arithmetic<U>::value>::type> {
+  using result_type = typename MaxExponentPromotion<T, U>::type;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U y) {
+    return IsGreater<T, U>::Test(x, y) ? saturated_cast<V>(x)
+                                       : saturated_cast<V>(y);
+  }
+};
+
+template <typename T, typename U, class Enable = void>
+struct ClampedMinOp {};
+
+template <typename T, typename U>
+struct ClampedMinOp<
+    T,
+    U,
+    typename std::enable_if<std::is_arithmetic<T>::value &&
+                            std::is_arithmetic<U>::value>::type> {
+  using result_type = typename LowestValuePromotion<T, U>::type;
+  template <typename V = result_type>
+  static constexpr V Do(T x, U y) {
+    return IsLess<T, U>::Test(x, y) ? saturated_cast<V>(x)
+                                    : saturated_cast<V>(y);
+  }
+};
+
+// This is just boilerplate that wraps the standard floating point arithmetic.
+// A macro isn't the nicest solution, but it beats rewriting these repeatedly.
+#define BASE_FLOAT_ARITHMETIC_OPS(NAME, OP)                              \
+  template <typename T, typename U>                                      \
+  struct Clamped##NAME##Op<                                              \
+      T, U,                                                              \
+      typename std::enable_if<std::is_floating_point<T>::value ||        \
+                              std::is_floating_point<U>::value>::type> { \
+    using result_type = typename MaxExponentPromotion<T, U>::type;       \
+    template <typename V = result_type>                                  \
+    static constexpr V Do(T x, U y) {                                    \
+      return saturated_cast<V>(x OP y);                                  \
+    }                                                                    \
+  };
+
+BASE_FLOAT_ARITHMETIC_OPS(Add, +)
+BASE_FLOAT_ARITHMETIC_OPS(Sub, -)
+BASE_FLOAT_ARITHMETIC_OPS(Mul, *)
+BASE_FLOAT_ARITHMETIC_OPS(Div, /)
+
+#undef BASE_FLOAT_ARITHMETIC_OPS
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_NUMERICS_CLAMPED_MATH_IMPL_H_
diff --git a/base/numerics/math_constants.h b/base/numerics/math_constants.h
new file mode 100644
index 0000000..9a5b8ef
--- /dev/null
+++ b/base/numerics/math_constants.h
@@ -0,0 +1,15 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_MATH_CONSTANTS_H_
+#define BASE_NUMERICS_MATH_CONSTANTS_H_
+
+namespace base {
+
+constexpr double kPiDouble = 3.14159265358979323846;
+constexpr float kPiFloat = 3.14159265358979323846f;
+
+}  // namespace base
+
+#endif  // BASE_NUMERICS_MATH_CONSTANTS_H_
diff --git a/base/numerics/ranges.h b/base/numerics/ranges.h
new file mode 100644
index 0000000..f19320c
--- /dev/null
+++ b/base/numerics/ranges.h
@@ -0,0 +1,27 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_RANGES_H_
+#define BASE_NUMERICS_RANGES_H_
+
+#include <algorithm>
+#include <cmath>
+
+namespace base {
+
+// To be replaced with std::clamp() from C++17, someday.
+template <class T>
+constexpr const T& ClampToRange(const T& value, const T& min, const T& max) {
+  return std::min(std::max(value, min), max);
+}
+
+template <typename T>
+constexpr bool IsApproximatelyEqual(T lhs, T rhs, T tolerance) {
+  static_assert(std::is_arithmetic<T>::value, "Argument must be arithmetic");
+  return std::abs(rhs - lhs) <= tolerance;
+}
+
+}  // namespace base
+
+#endif  // BASE_NUMERICS_RANGES_H_
diff --git a/base/numerics/safe_conversions.h b/base/numerics/safe_conversions.h
new file mode 100644
index 0000000..9284f8f
--- /dev/null
+++ b/base/numerics/safe_conversions.h
@@ -0,0 +1,344 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_SAFE_CONVERSIONS_H_
+#define BASE_NUMERICS_SAFE_CONVERSIONS_H_
+
+#include <stddef.h>
+
+#include <limits>
+#include <ostream>
+#include <type_traits>
+
+#include "base/numerics/safe_conversions_impl.h"
+
+#if !defined(__native_client__) && (defined(__ARMEL__) || defined(__arch64__))
+#include "base/numerics/safe_conversions_arm_impl.h"
+#define BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS (1)
+#else
+#define BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS (0)
+#endif
+
+namespace base {
+namespace internal {
+
+#if !BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS
+template <typename Dst, typename Src>
+struct SaturateFastAsmOp {
+  static const bool is_supported = false;
+  static constexpr Dst Do(Src) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<Dst>();
+  }
+};
+#endif  // BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS
+#undef BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS
+
+// The following special case a few specific integer conversions where we can
+// eke out better performance than range checking.
+template <typename Dst, typename Src, typename Enable = void>
+struct IsValueInRangeFastOp {
+  static const bool is_supported = false;
+  static constexpr bool Do(Src value) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<bool>();
+  }
+};
+
+// Signed to signed range comparison.
+template <typename Dst, typename Src>
+struct IsValueInRangeFastOp<
+    Dst,
+    Src,
+    typename std::enable_if<
+        std::is_integral<Dst>::value && std::is_integral<Src>::value &&
+        std::is_signed<Dst>::value && std::is_signed<Src>::value &&
+        !IsTypeInRangeForNumericType<Dst, Src>::value>::type> {
+  static const bool is_supported = true;
+
+  static constexpr bool Do(Src value) {
+    // Just downcast to the smaller type, sign extend it back to the original
+    // type, and then see if it matches the original value.
+    return value == static_cast<Dst>(value);
+  }
+};
+
+// Signed to unsigned range comparison.
+template <typename Dst, typename Src>
+struct IsValueInRangeFastOp<
+    Dst,
+    Src,
+    typename std::enable_if<
+        std::is_integral<Dst>::value && std::is_integral<Src>::value &&
+        !std::is_signed<Dst>::value && std::is_signed<Src>::value &&
+        !IsTypeInRangeForNumericType<Dst, Src>::value>::type> {
+  static const bool is_supported = true;
+
+  static constexpr bool Do(Src value) {
+    // We cast a signed as unsigned to overflow negative values to the top,
+    // then compare against whichever maximum is smaller, as our upper bound.
+    return as_unsigned(value) <= as_unsigned(CommonMax<Src, Dst>());
+  }
+};
+
+// Convenience function that returns true if the supplied value is in range
+// for the destination type.
+template <typename Dst, typename Src>
+constexpr bool IsValueInRangeForNumericType(Src value) {
+  using SrcType = typename internal::UnderlyingType<Src>::type;
+  return internal::IsValueInRangeFastOp<Dst, SrcType>::is_supported
+             ? internal::IsValueInRangeFastOp<Dst, SrcType>::Do(
+                   static_cast<SrcType>(value))
+             : internal::DstRangeRelationToSrcRange<Dst>(
+                   static_cast<SrcType>(value))
+                   .IsValid();
+}
+
+// checked_cast<> is analogous to static_cast<> for numeric types,
+// except that it CHECKs that the specified numeric conversion will not
+// overflow or underflow. NaN source will always trigger a CHECK.
+template <typename Dst,
+          class CheckHandler = internal::CheckOnFailure,
+          typename Src>
+constexpr Dst checked_cast(Src value) {
+  // This throws a compile-time error on evaluating the constexpr if it can be
+  // determined at compile-time as failing, otherwise it will CHECK at runtime.
+  using SrcType = typename internal::UnderlyingType<Src>::type;
+  return BASE_NUMERICS_LIKELY((IsValueInRangeForNumericType<Dst>(value)))
+             ? static_cast<Dst>(static_cast<SrcType>(value))
+             : CheckHandler::template HandleFailure<Dst>();
+}
+
+// Default boundaries for integral/float: max/infinity, lowest/-infinity, 0/NaN.
+// You may provide your own limits (e.g. to saturated_cast) so long as you
+// implement all of the static constexpr member functions in the class below.
+template <typename T>
+struct SaturationDefaultLimits : public std::numeric_limits<T> {
+  static constexpr T NaN() {
+    return std::numeric_limits<T>::has_quiet_NaN
+               ? std::numeric_limits<T>::quiet_NaN()
+               : T();
+  }
+  using std::numeric_limits<T>::max;
+  static constexpr T Overflow() {
+    return std::numeric_limits<T>::has_infinity
+               ? std::numeric_limits<T>::infinity()
+               : std::numeric_limits<T>::max();
+  }
+  using std::numeric_limits<T>::lowest;
+  static constexpr T Underflow() {
+    return std::numeric_limits<T>::has_infinity
+               ? std::numeric_limits<T>::infinity() * -1
+               : std::numeric_limits<T>::lowest();
+  }
+};
+
+template <typename Dst, template <typename> class S, typename Src>
+constexpr Dst saturated_cast_impl(Src value, RangeCheck constraint) {
+  // For some reason clang generates much better code when the branch is
+  // structured exactly this way, rather than a sequence of checks.
+  return !constraint.IsOverflowFlagSet()
+             ? (!constraint.IsUnderflowFlagSet() ? static_cast<Dst>(value)
+                                                 : S<Dst>::Underflow())
+             // Skip this check for integral Src, which cannot be NaN.
+             : (std::is_integral<Src>::value || !constraint.IsUnderflowFlagSet()
+                    ? S<Dst>::Overflow()
+                    : S<Dst>::NaN());
+}
+
+// We can reduce the number of conditions and get slightly better performance
+// for normal signed and unsigned integer ranges. And in the specific case of
+// Arm, we can use the optimized saturation instructions.
+template <typename Dst, typename Src, typename Enable = void>
+struct SaturateFastOp {
+  static const bool is_supported = false;
+  static constexpr Dst Do(Src value) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<Dst>();
+  }
+};
+
+template <typename Dst, typename Src>
+struct SaturateFastOp<
+    Dst,
+    Src,
+    typename std::enable_if<std::is_integral<Src>::value &&
+                            std::is_integral<Dst>::value>::type> {
+  static const bool is_supported = true;
+  static Dst Do(Src value) {
+    if (SaturateFastAsmOp<Dst, Src>::is_supported)
+      return SaturateFastAsmOp<Dst, Src>::Do(value);
+
+    // The exact order of the following is structured to hit the correct
+    // optimization heuristics across compilers. Do not change without
+    // checking the emitted code.
+    Dst saturated = CommonMaxOrMin<Dst, Src>(
+        IsMaxInRangeForNumericType<Dst, Src>() ||
+        (!IsMinInRangeForNumericType<Dst, Src>() && IsValueNegative(value)));
+    return BASE_NUMERICS_LIKELY(IsValueInRangeForNumericType<Dst>(value))
+               ? static_cast<Dst>(value)
+               : saturated;
+  }
+};
+
+// saturated_cast<> is analogous to static_cast<> for numeric types, except
+// that the specified numeric conversion will saturate by default rather than
+// overflow or underflow, and NaN assignment to an integral will return 0.
+// All boundary condition behaviors can be overriden with a custom handler.
+template <typename Dst,
+          template <typename> class SaturationHandler = SaturationDefaultLimits,
+          typename Src>
+constexpr Dst saturated_cast(Src value) {
+  using SrcType = typename UnderlyingType<Src>::type;
+  return !IsCompileTimeConstant(value) &&
+                 SaturateFastOp<Dst, SrcType>::is_supported &&
+                 std::is_same<SaturationHandler<Dst>,
+                              SaturationDefaultLimits<Dst>>::value
+             ? SaturateFastOp<Dst, SrcType>::Do(static_cast<SrcType>(value))
+             : saturated_cast_impl<Dst, SaturationHandler, SrcType>(
+                   static_cast<SrcType>(value),
+                   DstRangeRelationToSrcRange<Dst, SaturationHandler, SrcType>(
+                       static_cast<SrcType>(value)));
+}
+
+// strict_cast<> is analogous to static_cast<> for numeric types, except that
+// it will cause a compile failure if the destination type is not large enough
+// to contain any value in the source type. It performs no runtime checking.
+template <typename Dst, typename Src>
+constexpr Dst strict_cast(Src value) {
+  using SrcType = typename UnderlyingType<Src>::type;
+  static_assert(UnderlyingType<Src>::is_numeric, "Argument must be numeric.");
+  static_assert(std::is_arithmetic<Dst>::value, "Result must be numeric.");
+
+  // If you got here from a compiler error, it's because you tried to assign
+  // from a source type to a destination type that has insufficient range.
+  // The solution may be to change the destination type you're assigning to,
+  // and use one large enough to represent the source.
+  // Alternatively, you may be better served with the checked_cast<> or
+  // saturated_cast<> template functions for your particular use case.
+  static_assert(StaticDstRangeRelationToSrcRange<Dst, SrcType>::value ==
+                    NUMERIC_RANGE_CONTAINED,
+                "The source type is out of range for the destination type. "
+                "Please see strict_cast<> comments for more information.");
+
+  return static_cast<Dst>(static_cast<SrcType>(value));
+}
+
+// Some wrappers to statically check that a type is in range.
+template <typename Dst, typename Src, class Enable = void>
+struct IsNumericRangeContained {
+  static const bool value = false;
+};
+
+template <typename Dst, typename Src>
+struct IsNumericRangeContained<
+    Dst,
+    Src,
+    typename std::enable_if<ArithmeticOrUnderlyingEnum<Dst>::value &&
+                            ArithmeticOrUnderlyingEnum<Src>::value>::type> {
+  static const bool value = StaticDstRangeRelationToSrcRange<Dst, Src>::value ==
+                            NUMERIC_RANGE_CONTAINED;
+};
+
+// StrictNumeric implements compile time range checking between numeric types by
+// wrapping assignment operations in a strict_cast. This class is intended to be
+// used for function arguments and return types, to ensure the destination type
+// can always contain the source type. This is essentially the same as enforcing
+// -Wconversion in gcc and C4302 warnings on MSVC, but it can be applied
+// incrementally at API boundaries, making it easier to convert code so that it
+// compiles cleanly with truncation warnings enabled.
+// This template should introduce no runtime overhead, but it also provides no
+// runtime checking of any of the associated mathematical operations. Use
+// CheckedNumeric for runtime range checks of the actual value being assigned.
+template <typename T>
+class StrictNumeric {
+ public:
+  using type = T;
+
+  constexpr StrictNumeric() : value_(0) {}
+
+  // Copy constructor.
+  template <typename Src>
+  constexpr StrictNumeric(const StrictNumeric<Src>& rhs)
+      : value_(strict_cast<T>(rhs.value_)) {}
+
+  // This is not an explicit constructor because we implicitly upgrade regular
+  // numerics to StrictNumerics to make them easier to use.
+  template <typename Src>
+  constexpr StrictNumeric(Src value)  // NOLINT(runtime/explicit)
+      : value_(strict_cast<T>(value)) {}
+
+  // If you got here from a compiler error, it's because you tried to assign
+  // from a source type to a destination type that has insufficient range.
+  // The solution may be to change the destination type you're assigning to,
+  // and use one large enough to represent the source.
+  // If you're assigning from a CheckedNumeric<> class, you may be able to use
+  // the AssignIfValid() member function, specify a narrower destination type to
+  // the member value functions (e.g. val.template ValueOrDie<Dst>()), use one
+  // of the value helper functions (e.g. ValueOrDieForType<Dst>(val)).
+  // If you've encountered an _ambiguous overload_ you can use a static_cast<>
+  // to explicitly cast the result to the destination type.
+  // If none of that works, you may be better served with the checked_cast<> or
+  // saturated_cast<> template functions for your particular use case.
+  template <typename Dst,
+            typename std::enable_if<
+                IsNumericRangeContained<Dst, T>::value>::type* = nullptr>
+  constexpr operator Dst() const {
+    return static_cast<typename ArithmeticOrUnderlyingEnum<Dst>::type>(value_);
+  }
+
+ private:
+  const T value_;
+};
+
+// Convience wrapper returns a StrictNumeric from the provided arithmetic type.
+template <typename T>
+constexpr StrictNumeric<typename UnderlyingType<T>::type> MakeStrictNum(
+    const T value) {
+  return value;
+}
+
+// Overload the ostream output operator to make logging work nicely.
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const StrictNumeric<T>& value) {
+  os << static_cast<T>(value);
+  return os;
+}
+
+#define BASE_NUMERIC_COMPARISON_OPERATORS(CLASS, NAME, OP)              \
+  template <typename L, typename R,                                     \
+            typename std::enable_if<                                    \
+                internal::Is##CLASS##Op<L, R>::value>::type* = nullptr> \
+  constexpr bool operator OP(const L lhs, const R rhs) {                \
+    return SafeCompare<NAME, typename UnderlyingType<L>::type,          \
+                       typename UnderlyingType<R>::type>(lhs, rhs);     \
+  }
+
+BASE_NUMERIC_COMPARISON_OPERATORS(Strict, IsLess, <);
+BASE_NUMERIC_COMPARISON_OPERATORS(Strict, IsLessOrEqual, <=);
+BASE_NUMERIC_COMPARISON_OPERATORS(Strict, IsGreater, >);
+BASE_NUMERIC_COMPARISON_OPERATORS(Strict, IsGreaterOrEqual, >=);
+BASE_NUMERIC_COMPARISON_OPERATORS(Strict, IsEqual, ==);
+BASE_NUMERIC_COMPARISON_OPERATORS(Strict, IsNotEqual, !=);
+
+};  // namespace internal
+
+using internal::as_signed;
+using internal::as_unsigned;
+using internal::checked_cast;
+using internal::strict_cast;
+using internal::saturated_cast;
+using internal::SafeUnsignedAbs;
+using internal::StrictNumeric;
+using internal::MakeStrictNum;
+using internal::IsValueInRangeForNumericType;
+using internal::IsTypeInRangeForNumericType;
+using internal::IsValueNegative;
+
+// Explicitly make a shorter size_t alias for convenience.
+using SizeT = StrictNumeric<size_t>;
+
+}  // namespace base
+
+#endif  // BASE_NUMERICS_SAFE_CONVERSIONS_H_
diff --git a/base/numerics/safe_conversions_arm_impl.h b/base/numerics/safe_conversions_arm_impl.h
new file mode 100644
index 0000000..da5813f
--- /dev/null
+++ b/base/numerics/safe_conversions_arm_impl.h
@@ -0,0 +1,51 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_
+#define BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_
+
+#include <cassert>
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/safe_conversions_impl.h"
+
+namespace base {
+namespace internal {
+
+// Fast saturation to a destination type.
+template <typename Dst, typename Src>
+struct SaturateFastAsmOp {
+  static const bool is_supported =
+      std::is_signed<Src>::value && std::is_integral<Dst>::value &&
+      std::is_integral<Src>::value &&
+      IntegerBitsPlusSign<Src>::value <= IntegerBitsPlusSign<int32_t>::value &&
+      IntegerBitsPlusSign<Dst>::value <= IntegerBitsPlusSign<int32_t>::value &&
+      !IsTypeInRangeForNumericType<Dst, Src>::value;
+
+  __attribute__((always_inline)) static Dst Do(Src value) {
+    int32_t src = value;
+    typename std::conditional<std::is_signed<Dst>::value, int32_t,
+                              uint32_t>::type result;
+    if (std::is_signed<Dst>::value) {
+      asm("ssat %[dst], %[shift], %[src]"
+          : [dst] "=r"(result)
+          : [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value <= 32
+                                            ? IntegerBitsPlusSign<Dst>::value
+                                            : 32));
+    } else {
+      asm("usat %[dst], %[shift], %[src]"
+          : [dst] "=r"(result)
+          : [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value < 32
+                                            ? IntegerBitsPlusSign<Dst>::value
+                                            : 31));
+    }
+    return static_cast<Dst>(result);
+  }
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_
diff --git a/base/numerics/safe_conversions_impl.h b/base/numerics/safe_conversions_impl.h
new file mode 100644
index 0000000..2516204
--- /dev/null
+++ b/base/numerics/safe_conversions_impl.h
@@ -0,0 +1,850 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
+#define BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
+
+#include <stdint.h>
+
+#include <limits>
+#include <type_traits>
+
+#if defined(__GNUC__) || defined(__clang__)
+#define BASE_NUMERICS_LIKELY(x) __builtin_expect(!!(x), 1)
+#define BASE_NUMERICS_UNLIKELY(x) __builtin_expect(!!(x), 0)
+#else
+#define BASE_NUMERICS_LIKELY(x) (x)
+#define BASE_NUMERICS_UNLIKELY(x) (x)
+#endif
+
+namespace base {
+namespace internal {
+
+// The std library doesn't provide a binary max_exponent for integers, however
+// we can compute an analog using std::numeric_limits<>::digits.
+template <typename NumericType>
+struct MaxExponent {
+  static const int value = std::is_floating_point<NumericType>::value
+                               ? std::numeric_limits<NumericType>::max_exponent
+                               : std::numeric_limits<NumericType>::digits + 1;
+};
+
+// The number of bits (including the sign) in an integer. Eliminates sizeof
+// hacks.
+template <typename NumericType>
+struct IntegerBitsPlusSign {
+  static const int value = std::numeric_limits<NumericType>::digits +
+                           std::is_signed<NumericType>::value;
+};
+
+// Helper templates for integer manipulations.
+
+template <typename Integer>
+struct PositionOfSignBit {
+  static const size_t value = IntegerBitsPlusSign<Integer>::value - 1;
+};
+
+// Determines if a numeric value is negative without throwing compiler
+// warnings on: unsigned(value) < 0.
+template <typename T,
+          typename std::enable_if<std::is_signed<T>::value>::type* = nullptr>
+constexpr bool IsValueNegative(T value) {
+  static_assert(std::is_arithmetic<T>::value, "Argument must be numeric.");
+  return value < 0;
+}
+
+template <typename T,
+          typename std::enable_if<!std::is_signed<T>::value>::type* = nullptr>
+constexpr bool IsValueNegative(T) {
+  static_assert(std::is_arithmetic<T>::value, "Argument must be numeric.");
+  return false;
+}
+
+// This performs a fast negation, returning a signed value. It works on unsigned
+// arguments, but probably doesn't do what you want for any unsigned value
+// larger than max / 2 + 1 (i.e. signed min cast to unsigned).
+template <typename T>
+constexpr typename std::make_signed<T>::type ConditionalNegate(
+    T x,
+    bool is_negative) {
+  static_assert(std::is_integral<T>::value, "Type must be integral");
+  using SignedT = typename std::make_signed<T>::type;
+  using UnsignedT = typename std::make_unsigned<T>::type;
+  return static_cast<SignedT>(
+      (static_cast<UnsignedT>(x) ^ -SignedT(is_negative)) + is_negative);
+}
+
+// This performs a safe, absolute value via unsigned overflow.
+template <typename T>
+constexpr typename std::make_unsigned<T>::type SafeUnsignedAbs(T value) {
+  static_assert(std::is_integral<T>::value, "Type must be integral");
+  using UnsignedT = typename std::make_unsigned<T>::type;
+  return IsValueNegative(value) ? 0 - static_cast<UnsignedT>(value)
+                                : static_cast<UnsignedT>(value);
+}
+
+// This allows us to switch paths on known compile-time constants.
+#if defined(__clang__) || defined(__GNUC__)
+constexpr bool CanDetectCompileTimeConstant() {
+  return true;
+}
+template <typename T>
+constexpr bool IsCompileTimeConstant(const T v) {
+  return __builtin_constant_p(v);
+}
+#else
+constexpr bool CanDetectCompileTimeConstant() {
+  return false;
+}
+template <typename T>
+constexpr bool IsCompileTimeConstant(const T) {
+  return false;
+}
+#endif
+template <typename T>
+constexpr bool MustTreatAsConstexpr(const T v) {
+  // Either we can't detect a compile-time constant, and must always use the
+  // constexpr path, or we know we have a compile-time constant.
+  return !CanDetectCompileTimeConstant() || IsCompileTimeConstant(v);
+}
+
+// Forces a crash, like a CHECK(false). Used for numeric boundary errors.
+// Also used in a constexpr template to trigger a compilation failure on
+// an error condition.
+struct CheckOnFailure {
+  template <typename T>
+  static T HandleFailure() {
+#if defined(_MSC_VER)
+    __debugbreak();
+#elif defined(__GNUC__) || defined(__clang__)
+    __builtin_trap();
+#else
+    ((void)(*(volatile char*)0 = 0));
+#endif
+    return T();
+  }
+};
+
+enum IntegerRepresentation {
+  INTEGER_REPRESENTATION_UNSIGNED,
+  INTEGER_REPRESENTATION_SIGNED
+};
+
+// A range for a given nunmeric Src type is contained for a given numeric Dst
+// type if both numeric_limits<Src>::max() <= numeric_limits<Dst>::max() and
+// numeric_limits<Src>::lowest() >= numeric_limits<Dst>::lowest() are true.
+// We implement this as template specializations rather than simple static
+// comparisons to ensure type correctness in our comparisons.
+enum NumericRangeRepresentation {
+  NUMERIC_RANGE_NOT_CONTAINED,
+  NUMERIC_RANGE_CONTAINED
+};
+
+// Helper templates to statically determine if our destination type can contain
+// maximum and minimum values represented by the source type.
+
+template <typename Dst,
+          typename Src,
+          IntegerRepresentation DstSign = std::is_signed<Dst>::value
+                                              ? INTEGER_REPRESENTATION_SIGNED
+                                              : INTEGER_REPRESENTATION_UNSIGNED,
+          IntegerRepresentation SrcSign = std::is_signed<Src>::value
+                                              ? INTEGER_REPRESENTATION_SIGNED
+                                              : INTEGER_REPRESENTATION_UNSIGNED>
+struct StaticDstRangeRelationToSrcRange;
+
+// Same sign: Dst is guaranteed to contain Src only if its range is equal or
+// larger.
+template <typename Dst, typename Src, IntegerRepresentation Sign>
+struct StaticDstRangeRelationToSrcRange<Dst, Src, Sign, Sign> {
+  static const NumericRangeRepresentation value =
+      MaxExponent<Dst>::value >= MaxExponent<Src>::value
+          ? NUMERIC_RANGE_CONTAINED
+          : NUMERIC_RANGE_NOT_CONTAINED;
+};
+
+// Unsigned to signed: Dst is guaranteed to contain source only if its range is
+// larger.
+template <typename Dst, typename Src>
+struct StaticDstRangeRelationToSrcRange<Dst,
+                                        Src,
+                                        INTEGER_REPRESENTATION_SIGNED,
+                                        INTEGER_REPRESENTATION_UNSIGNED> {
+  static const NumericRangeRepresentation value =
+      MaxExponent<Dst>::value > MaxExponent<Src>::value
+          ? NUMERIC_RANGE_CONTAINED
+          : NUMERIC_RANGE_NOT_CONTAINED;
+};
+
+// Signed to unsigned: Dst cannot be statically determined to contain Src.
+template <typename Dst, typename Src>
+struct StaticDstRangeRelationToSrcRange<Dst,
+                                        Src,
+                                        INTEGER_REPRESENTATION_UNSIGNED,
+                                        INTEGER_REPRESENTATION_SIGNED> {
+  static const NumericRangeRepresentation value = NUMERIC_RANGE_NOT_CONTAINED;
+};
+
+// This class wraps the range constraints as separate booleans so the compiler
+// can identify constants and eliminate unused code paths.
+class RangeCheck {
+ public:
+  constexpr RangeCheck(bool is_in_lower_bound, bool is_in_upper_bound)
+      : is_underflow_(!is_in_lower_bound), is_overflow_(!is_in_upper_bound) {}
+  constexpr RangeCheck() : is_underflow_(0), is_overflow_(0) {}
+  constexpr bool IsValid() const { return !is_overflow_ && !is_underflow_; }
+  constexpr bool IsInvalid() const { return is_overflow_ && is_underflow_; }
+  constexpr bool IsOverflow() const { return is_overflow_ && !is_underflow_; }
+  constexpr bool IsUnderflow() const { return !is_overflow_ && is_underflow_; }
+  constexpr bool IsOverflowFlagSet() const { return is_overflow_; }
+  constexpr bool IsUnderflowFlagSet() const { return is_underflow_; }
+  constexpr bool operator==(const RangeCheck rhs) const {
+    return is_underflow_ == rhs.is_underflow_ &&
+           is_overflow_ == rhs.is_overflow_;
+  }
+  constexpr bool operator!=(const RangeCheck rhs) const {
+    return !(*this == rhs);
+  }
+
+ private:
+  // Do not change the order of these member variables. The integral conversion
+  // optimization depends on this exact order.
+  const bool is_underflow_;
+  const bool is_overflow_;
+};
+
+// The following helper template addresses a corner case in range checks for
+// conversion from a floating-point type to an integral type of smaller range
+// but larger precision (e.g. float -> unsigned). The problem is as follows:
+//   1. Integral maximum is always one less than a power of two, so it must be
+//      truncated to fit the mantissa of the floating point. The direction of
+//      rounding is implementation defined, but by default it's always IEEE
+//      floats, which round to nearest and thus result in a value of larger
+//      magnitude than the integral value.
+//      Example: float f = UINT_MAX; // f is 4294967296f but UINT_MAX
+//                                   // is 4294967295u.
+//   2. If the floating point value is equal to the promoted integral maximum
+//      value, a range check will erroneously pass.
+//      Example: (4294967296f <= 4294967295u) // This is true due to a precision
+//                                            // loss in rounding up to float.
+//   3. When the floating point value is then converted to an integral, the
+//      resulting value is out of range for the target integral type and
+//      thus is implementation defined.
+//      Example: unsigned u = (float)INT_MAX; // u will typically overflow to 0.
+// To fix this bug we manually truncate the maximum value when the destination
+// type is an integral of larger precision than the source floating-point type,
+// such that the resulting maximum is represented exactly as a floating point.
+template <typename Dst, typename Src, template <typename> class Bounds>
+struct NarrowingRange {
+  using SrcLimits = std::numeric_limits<Src>;
+  using DstLimits = typename std::numeric_limits<Dst>;
+
+  // Computes the mask required to make an accurate comparison between types.
+  static const int kShift =
+      (MaxExponent<Src>::value > MaxExponent<Dst>::value &&
+       SrcLimits::digits < DstLimits::digits)
+          ? (DstLimits::digits - SrcLimits::digits)
+          : 0;
+  template <
+      typename T,
+      typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
+
+  // Masks out the integer bits that are beyond the precision of the
+  // intermediate type used for comparison.
+  static constexpr T Adjust(T value) {
+    static_assert(std::is_same<T, Dst>::value, "");
+    static_assert(kShift < DstLimits::digits, "");
+    return static_cast<T>(
+        ConditionalNegate(SafeUnsignedAbs(value) & ~((T(1) << kShift) - T(1)),
+                          IsValueNegative(value)));
+  }
+
+  template <typename T,
+            typename std::enable_if<std::is_floating_point<T>::value>::type* =
+                nullptr>
+  static constexpr T Adjust(T value) {
+    static_assert(std::is_same<T, Dst>::value, "");
+    static_assert(kShift == 0, "");
+    return value;
+  }
+
+  static constexpr Dst max() { return Adjust(Bounds<Dst>::max()); }
+  static constexpr Dst lowest() { return Adjust(Bounds<Dst>::lowest()); }
+};
+
+template <typename Dst,
+          typename Src,
+          template <typename> class Bounds,
+          IntegerRepresentation DstSign = std::is_signed<Dst>::value
+                                              ? INTEGER_REPRESENTATION_SIGNED
+                                              : INTEGER_REPRESENTATION_UNSIGNED,
+          IntegerRepresentation SrcSign = std::is_signed<Src>::value
+                                              ? INTEGER_REPRESENTATION_SIGNED
+                                              : INTEGER_REPRESENTATION_UNSIGNED,
+          NumericRangeRepresentation DstRange =
+              StaticDstRangeRelationToSrcRange<Dst, Src>::value>
+struct DstRangeRelationToSrcRangeImpl;
+
+// The following templates are for ranges that must be verified at runtime. We
+// split it into checks based on signedness to avoid confusing casts and
+// compiler warnings on signed an unsigned comparisons.
+
+// Same sign narrowing: The range is contained for normal limits.
+template <typename Dst,
+          typename Src,
+          template <typename> class Bounds,
+          IntegerRepresentation DstSign,
+          IntegerRepresentation SrcSign>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      Bounds,
+                                      DstSign,
+                                      SrcSign,
+                                      NUMERIC_RANGE_CONTAINED> {
+  static constexpr RangeCheck Check(Src value) {
+    using SrcLimits = std::numeric_limits<Src>;
+    using DstLimits = NarrowingRange<Dst, Src, Bounds>;
+    return RangeCheck(
+        static_cast<Dst>(SrcLimits::lowest()) >= DstLimits::lowest() ||
+            static_cast<Dst>(value) >= DstLimits::lowest(),
+        static_cast<Dst>(SrcLimits::max()) <= DstLimits::max() ||
+            static_cast<Dst>(value) <= DstLimits::max());
+  }
+};
+
+// Signed to signed narrowing: Both the upper and lower boundaries may be
+// exceeded for standard limits.
+template <typename Dst, typename Src, template <typename> class Bounds>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      Bounds,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static constexpr RangeCheck Check(Src value) {
+    using DstLimits = NarrowingRange<Dst, Src, Bounds>;
+    return RangeCheck(value >= DstLimits::lowest(), value <= DstLimits::max());
+  }
+};
+
+// Unsigned to unsigned narrowing: Only the upper bound can be exceeded for
+// standard limits.
+template <typename Dst, typename Src, template <typename> class Bounds>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      Bounds,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static constexpr RangeCheck Check(Src value) {
+    using DstLimits = NarrowingRange<Dst, Src, Bounds>;
+    return RangeCheck(
+        DstLimits::lowest() == Dst(0) || value >= DstLimits::lowest(),
+        value <= DstLimits::max());
+  }
+};
+
+// Unsigned to signed: Only the upper bound can be exceeded for standard limits.
+template <typename Dst, typename Src, template <typename> class Bounds>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      Bounds,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static constexpr RangeCheck Check(Src value) {
+    using DstLimits = NarrowingRange<Dst, Src, Bounds>;
+    using Promotion = decltype(Src() + Dst());
+    return RangeCheck(DstLimits::lowest() <= Dst(0) ||
+                          static_cast<Promotion>(value) >=
+                              static_cast<Promotion>(DstLimits::lowest()),
+                      static_cast<Promotion>(value) <=
+                          static_cast<Promotion>(DstLimits::max()));
+  }
+};
+
+// Signed to unsigned: The upper boundary may be exceeded for a narrower Dst,
+// and any negative value exceeds the lower boundary for standard limits.
+template <typename Dst, typename Src, template <typename> class Bounds>
+struct DstRangeRelationToSrcRangeImpl<Dst,
+                                      Src,
+                                      Bounds,
+                                      INTEGER_REPRESENTATION_UNSIGNED,
+                                      INTEGER_REPRESENTATION_SIGNED,
+                                      NUMERIC_RANGE_NOT_CONTAINED> {
+  static constexpr RangeCheck Check(Src value) {
+    using SrcLimits = std::numeric_limits<Src>;
+    using DstLimits = NarrowingRange<Dst, Src, Bounds>;
+    using Promotion = decltype(Src() + Dst());
+    return RangeCheck(
+        value >= Src(0) && (DstLimits::lowest() == 0 ||
+                            static_cast<Dst>(value) >= DstLimits::lowest()),
+        static_cast<Promotion>(SrcLimits::max()) <=
+                static_cast<Promotion>(DstLimits::max()) ||
+            static_cast<Promotion>(value) <=
+                static_cast<Promotion>(DstLimits::max()));
+  }
+};
+
+// Simple wrapper for statically checking if a type's range is contained.
+template <typename Dst, typename Src>
+struct IsTypeInRangeForNumericType {
+  static const bool value = StaticDstRangeRelationToSrcRange<Dst, Src>::value ==
+                            NUMERIC_RANGE_CONTAINED;
+};
+
+template <typename Dst,
+          template <typename> class Bounds = std::numeric_limits,
+          typename Src>
+constexpr RangeCheck DstRangeRelationToSrcRange(Src value) {
+  static_assert(std::is_arithmetic<Src>::value, "Argument must be numeric.");
+  static_assert(std::is_arithmetic<Dst>::value, "Result must be numeric.");
+  static_assert(Bounds<Dst>::lowest() < Bounds<Dst>::max(), "");
+  return DstRangeRelationToSrcRangeImpl<Dst, Src, Bounds>::Check(value);
+}
+
+// Integer promotion templates used by the portable checked integer arithmetic.
+template <size_t Size, bool IsSigned>
+struct IntegerForDigitsAndSign;
+
+#define INTEGER_FOR_DIGITS_AND_SIGN(I)                          \
+  template <>                                                   \
+  struct IntegerForDigitsAndSign<IntegerBitsPlusSign<I>::value, \
+                                 std::is_signed<I>::value> {    \
+    using type = I;                                             \
+  }
+
+INTEGER_FOR_DIGITS_AND_SIGN(int8_t);
+INTEGER_FOR_DIGITS_AND_SIGN(uint8_t);
+INTEGER_FOR_DIGITS_AND_SIGN(int16_t);
+INTEGER_FOR_DIGITS_AND_SIGN(uint16_t);
+INTEGER_FOR_DIGITS_AND_SIGN(int32_t);
+INTEGER_FOR_DIGITS_AND_SIGN(uint32_t);
+INTEGER_FOR_DIGITS_AND_SIGN(int64_t);
+INTEGER_FOR_DIGITS_AND_SIGN(uint64_t);
+#undef INTEGER_FOR_DIGITS_AND_SIGN
+
+// WARNING: We have no IntegerForSizeAndSign<16, *>. If we ever add one to
+// support 128-bit math, then the ArithmeticPromotion template below will need
+// to be updated (or more likely replaced with a decltype expression).
+static_assert(IntegerBitsPlusSign<intmax_t>::value == 64,
+              "Max integer size not supported for this toolchain.");
+
+template <typename Integer, bool IsSigned = std::is_signed<Integer>::value>
+struct TwiceWiderInteger {
+  using type =
+      typename IntegerForDigitsAndSign<IntegerBitsPlusSign<Integer>::value * 2,
+                                       IsSigned>::type;
+};
+
+enum ArithmeticPromotionCategory {
+  LEFT_PROMOTION,  // Use the type of the left-hand argument.
+  RIGHT_PROMOTION  // Use the type of the right-hand argument.
+};
+
+// Determines the type that can represent the largest positive value.
+template <typename Lhs,
+          typename Rhs,
+          ArithmeticPromotionCategory Promotion =
+              (MaxExponent<Lhs>::value > MaxExponent<Rhs>::value)
+                  ? LEFT_PROMOTION
+                  : RIGHT_PROMOTION>
+struct MaxExponentPromotion;
+
+template <typename Lhs, typename Rhs>
+struct MaxExponentPromotion<Lhs, Rhs, LEFT_PROMOTION> {
+  using type = Lhs;
+};
+
+template <typename Lhs, typename Rhs>
+struct MaxExponentPromotion<Lhs, Rhs, RIGHT_PROMOTION> {
+  using type = Rhs;
+};
+
+// Determines the type that can represent the lowest arithmetic value.
+template <typename Lhs,
+          typename Rhs,
+          ArithmeticPromotionCategory Promotion =
+              std::is_signed<Lhs>::value
+                  ? (std::is_signed<Rhs>::value
+                         ? (MaxExponent<Lhs>::value > MaxExponent<Rhs>::value
+                                ? LEFT_PROMOTION
+                                : RIGHT_PROMOTION)
+                         : LEFT_PROMOTION)
+                  : (std::is_signed<Rhs>::value
+                         ? RIGHT_PROMOTION
+                         : (MaxExponent<Lhs>::value < MaxExponent<Rhs>::value
+                                ? LEFT_PROMOTION
+                                : RIGHT_PROMOTION))>
+struct LowestValuePromotion;
+
+template <typename Lhs, typename Rhs>
+struct LowestValuePromotion<Lhs, Rhs, LEFT_PROMOTION> {
+  using type = Lhs;
+};
+
+template <typename Lhs, typename Rhs>
+struct LowestValuePromotion<Lhs, Rhs, RIGHT_PROMOTION> {
+  using type = Rhs;
+};
+
+// Determines the type that is best able to represent an arithmetic result.
+template <
+    typename Lhs,
+    typename Rhs = Lhs,
+    bool is_intmax_type =
+        std::is_integral<typename MaxExponentPromotion<Lhs, Rhs>::type>::value&&
+            IntegerBitsPlusSign<typename MaxExponentPromotion<Lhs, Rhs>::type>::
+                value == IntegerBitsPlusSign<intmax_t>::value,
+    bool is_max_exponent =
+        StaticDstRangeRelationToSrcRange<
+            typename MaxExponentPromotion<Lhs, Rhs>::type,
+            Lhs>::value ==
+        NUMERIC_RANGE_CONTAINED&& StaticDstRangeRelationToSrcRange<
+            typename MaxExponentPromotion<Lhs, Rhs>::type,
+            Rhs>::value == NUMERIC_RANGE_CONTAINED>
+struct BigEnoughPromotion;
+
+// The side with the max exponent is big enough.
+template <typename Lhs, typename Rhs, bool is_intmax_type>
+struct BigEnoughPromotion<Lhs, Rhs, is_intmax_type, true> {
+  using type = typename MaxExponentPromotion<Lhs, Rhs>::type;
+  static const bool is_contained = true;
+};
+
+// We can use a twice wider type to fit.
+template <typename Lhs, typename Rhs>
+struct BigEnoughPromotion<Lhs, Rhs, false, false> {
+  using type =
+      typename TwiceWiderInteger<typename MaxExponentPromotion<Lhs, Rhs>::type,
+                                 std::is_signed<Lhs>::value ||
+                                     std::is_signed<Rhs>::value>::type;
+  static const bool is_contained = true;
+};
+
+// No type is large enough.
+template <typename Lhs, typename Rhs>
+struct BigEnoughPromotion<Lhs, Rhs, true, false> {
+  using type = typename MaxExponentPromotion<Lhs, Rhs>::type;
+  static const bool is_contained = false;
+};
+
+// We can statically check if operations on the provided types can wrap, so we
+// can skip the checked operations if they're not needed. So, for an integer we
+// care if the destination type preserves the sign and is twice the width of
+// the source.
+template <typename T, typename Lhs, typename Rhs = Lhs>
+struct IsIntegerArithmeticSafe {
+  static const bool value =
+      !std::is_floating_point<T>::value &&
+      !std::is_floating_point<Lhs>::value &&
+      !std::is_floating_point<Rhs>::value &&
+      std::is_signed<T>::value >= std::is_signed<Lhs>::value &&
+      IntegerBitsPlusSign<T>::value >= (2 * IntegerBitsPlusSign<Lhs>::value) &&
+      std::is_signed<T>::value >= std::is_signed<Rhs>::value &&
+      IntegerBitsPlusSign<T>::value >= (2 * IntegerBitsPlusSign<Rhs>::value);
+};
+
+// Promotes to a type that can represent any possible result of a binary
+// arithmetic operation with the source types.
+template <typename Lhs,
+          typename Rhs,
+          bool is_promotion_possible = IsIntegerArithmeticSafe<
+              typename std::conditional<std::is_signed<Lhs>::value ||
+                                            std::is_signed<Rhs>::value,
+                                        intmax_t,
+                                        uintmax_t>::type,
+              typename MaxExponentPromotion<Lhs, Rhs>::type>::value>
+struct FastIntegerArithmeticPromotion;
+
+template <typename Lhs, typename Rhs>
+struct FastIntegerArithmeticPromotion<Lhs, Rhs, true> {
+  using type =
+      typename TwiceWiderInteger<typename MaxExponentPromotion<Lhs, Rhs>::type,
+                                 std::is_signed<Lhs>::value ||
+                                     std::is_signed<Rhs>::value>::type;
+  static_assert(IsIntegerArithmeticSafe<type, Lhs, Rhs>::value, "");
+  static const bool is_contained = true;
+};
+
+template <typename Lhs, typename Rhs>
+struct FastIntegerArithmeticPromotion<Lhs, Rhs, false> {
+  using type = typename BigEnoughPromotion<Lhs, Rhs>::type;
+  static const bool is_contained = false;
+};
+
+// Extracts the underlying type from an enum.
+template <typename T, bool is_enum = std::is_enum<T>::value>
+struct ArithmeticOrUnderlyingEnum;
+
+template <typename T>
+struct ArithmeticOrUnderlyingEnum<T, true> {
+  using type = typename std::underlying_type<T>::type;
+  static const bool value = std::is_arithmetic<type>::value;
+};
+
+template <typename T>
+struct ArithmeticOrUnderlyingEnum<T, false> {
+  using type = T;
+  static const bool value = std::is_arithmetic<type>::value;
+};
+
+// The following are helper templates used in the CheckedNumeric class.
+template <typename T>
+class CheckedNumeric;
+
+template <typename T>
+class ClampedNumeric;
+
+template <typename T>
+class StrictNumeric;
+
+// Used to treat CheckedNumeric and arithmetic underlying types the same.
+template <typename T>
+struct UnderlyingType {
+  using type = typename ArithmeticOrUnderlyingEnum<T>::type;
+  static const bool is_numeric = std::is_arithmetic<type>::value;
+  static const bool is_checked = false;
+  static const bool is_clamped = false;
+  static const bool is_strict = false;
+};
+
+template <typename T>
+struct UnderlyingType<CheckedNumeric<T>> {
+  using type = T;
+  static const bool is_numeric = true;
+  static const bool is_checked = true;
+  static const bool is_clamped = false;
+  static const bool is_strict = false;
+};
+
+template <typename T>
+struct UnderlyingType<ClampedNumeric<T>> {
+  using type = T;
+  static const bool is_numeric = true;
+  static const bool is_checked = false;
+  static const bool is_clamped = true;
+  static const bool is_strict = false;
+};
+
+template <typename T>
+struct UnderlyingType<StrictNumeric<T>> {
+  using type = T;
+  static const bool is_numeric = true;
+  static const bool is_checked = false;
+  static const bool is_clamped = false;
+  static const bool is_strict = true;
+};
+
+template <typename L, typename R>
+struct IsCheckedOp {
+  static const bool value =
+      UnderlyingType<L>::is_numeric && UnderlyingType<R>::is_numeric &&
+      (UnderlyingType<L>::is_checked || UnderlyingType<R>::is_checked);
+};
+
+template <typename L, typename R>
+struct IsClampedOp {
+  static const bool value =
+      UnderlyingType<L>::is_numeric && UnderlyingType<R>::is_numeric &&
+      (UnderlyingType<L>::is_clamped || UnderlyingType<R>::is_clamped) &&
+      !(UnderlyingType<L>::is_checked || UnderlyingType<R>::is_checked);
+};
+
+template <typename L, typename R>
+struct IsStrictOp {
+  static const bool value =
+      UnderlyingType<L>::is_numeric && UnderlyingType<R>::is_numeric &&
+      (UnderlyingType<L>::is_strict || UnderlyingType<R>::is_strict) &&
+      !(UnderlyingType<L>::is_checked || UnderlyingType<R>::is_checked) &&
+      !(UnderlyingType<L>::is_clamped || UnderlyingType<R>::is_clamped);
+};
+
+// as_signed<> returns the supplied integral value (or integral castable
+// Numeric template) cast as a signed integral of equivalent precision.
+// I.e. it's mostly an alias for: static_cast<std::make_signed<T>::type>(t)
+template <typename Src>
+constexpr typename std::make_signed<
+    typename base::internal::UnderlyingType<Src>::type>::type
+as_signed(const Src value) {
+  static_assert(std::is_integral<decltype(as_signed(value))>::value,
+                "Argument must be a signed or unsigned integer type.");
+  return static_cast<decltype(as_signed(value))>(value);
+}
+
+// as_unsigned<> returns the supplied integral value (or integral castable
+// Numeric template) cast as an unsigned integral of equivalent precision.
+// I.e. it's mostly an alias for: static_cast<std::make_unsigned<T>::type>(t)
+template <typename Src>
+constexpr typename std::make_unsigned<
+    typename base::internal::UnderlyingType<Src>::type>::type
+as_unsigned(const Src value) {
+  static_assert(std::is_integral<decltype(as_unsigned(value))>::value,
+                "Argument must be a signed or unsigned integer type.");
+  return static_cast<decltype(as_unsigned(value))>(value);
+}
+
+template <typename L, typename R>
+constexpr bool IsLessImpl(const L lhs,
+                          const R rhs,
+                          const RangeCheck l_range,
+                          const RangeCheck r_range) {
+  return l_range.IsUnderflow() || r_range.IsOverflow() ||
+         (l_range == r_range &&
+          static_cast<decltype(lhs + rhs)>(lhs) <
+              static_cast<decltype(lhs + rhs)>(rhs));
+}
+
+template <typename L, typename R>
+struct IsLess {
+  static_assert(std::is_arithmetic<L>::value && std::is_arithmetic<R>::value,
+                "Types must be numeric.");
+  static constexpr bool Test(const L lhs, const R rhs) {
+    return IsLessImpl(lhs, rhs, DstRangeRelationToSrcRange<R>(lhs),
+                      DstRangeRelationToSrcRange<L>(rhs));
+  }
+};
+
+template <typename L, typename R>
+constexpr bool IsLessOrEqualImpl(const L lhs,
+                                 const R rhs,
+                                 const RangeCheck l_range,
+                                 const RangeCheck r_range) {
+  return l_range.IsUnderflow() || r_range.IsOverflow() ||
+         (l_range == r_range &&
+          static_cast<decltype(lhs + rhs)>(lhs) <=
+              static_cast<decltype(lhs + rhs)>(rhs));
+}
+
+template <typename L, typename R>
+struct IsLessOrEqual {
+  static_assert(std::is_arithmetic<L>::value && std::is_arithmetic<R>::value,
+                "Types must be numeric.");
+  static constexpr bool Test(const L lhs, const R rhs) {
+    return IsLessOrEqualImpl(lhs, rhs, DstRangeRelationToSrcRange<R>(lhs),
+                             DstRangeRelationToSrcRange<L>(rhs));
+  }
+};
+
+template <typename L, typename R>
+constexpr bool IsGreaterImpl(const L lhs,
+                             const R rhs,
+                             const RangeCheck l_range,
+                             const RangeCheck r_range) {
+  return l_range.IsOverflow() || r_range.IsUnderflow() ||
+         (l_range == r_range &&
+          static_cast<decltype(lhs + rhs)>(lhs) >
+              static_cast<decltype(lhs + rhs)>(rhs));
+}
+
+template <typename L, typename R>
+struct IsGreater {
+  static_assert(std::is_arithmetic<L>::value && std::is_arithmetic<R>::value,
+                "Types must be numeric.");
+  static constexpr bool Test(const L lhs, const R rhs) {
+    return IsGreaterImpl(lhs, rhs, DstRangeRelationToSrcRange<R>(lhs),
+                         DstRangeRelationToSrcRange<L>(rhs));
+  }
+};
+
+template <typename L, typename R>
+constexpr bool IsGreaterOrEqualImpl(const L lhs,
+                                    const R rhs,
+                                    const RangeCheck l_range,
+                                    const RangeCheck r_range) {
+  return l_range.IsOverflow() || r_range.IsUnderflow() ||
+         (l_range == r_range &&
+          static_cast<decltype(lhs + rhs)>(lhs) >=
+              static_cast<decltype(lhs + rhs)>(rhs));
+}
+
+template <typename L, typename R>
+struct IsGreaterOrEqual {
+  static_assert(std::is_arithmetic<L>::value && std::is_arithmetic<R>::value,
+                "Types must be numeric.");
+  static constexpr bool Test(const L lhs, const R rhs) {
+    return IsGreaterOrEqualImpl(lhs, rhs, DstRangeRelationToSrcRange<R>(lhs),
+                                DstRangeRelationToSrcRange<L>(rhs));
+  }
+};
+
+template <typename L, typename R>
+struct IsEqual {
+  static_assert(std::is_arithmetic<L>::value && std::is_arithmetic<R>::value,
+                "Types must be numeric.");
+  static constexpr bool Test(const L lhs, const R rhs) {
+    return DstRangeRelationToSrcRange<R>(lhs) ==
+               DstRangeRelationToSrcRange<L>(rhs) &&
+           static_cast<decltype(lhs + rhs)>(lhs) ==
+               static_cast<decltype(lhs + rhs)>(rhs);
+  }
+};
+
+template <typename L, typename R>
+struct IsNotEqual {
+  static_assert(std::is_arithmetic<L>::value && std::is_arithmetic<R>::value,
+                "Types must be numeric.");
+  static constexpr bool Test(const L lhs, const R rhs) {
+    return DstRangeRelationToSrcRange<R>(lhs) !=
+               DstRangeRelationToSrcRange<L>(rhs) ||
+           static_cast<decltype(lhs + rhs)>(lhs) !=
+               static_cast<decltype(lhs + rhs)>(rhs);
+  }
+};
+
+// These perform the actual math operations on the CheckedNumerics.
+// Binary arithmetic operations.
+template <template <typename, typename> class C, typename L, typename R>
+constexpr bool SafeCompare(const L lhs, const R rhs) {
+  static_assert(std::is_arithmetic<L>::value && std::is_arithmetic<R>::value,
+                "Types must be numeric.");
+  using Promotion = BigEnoughPromotion<L, R>;
+  using BigType = typename Promotion::type;
+  return Promotion::is_contained
+             // Force to a larger type for speed if both are contained.
+             ? C<BigType, BigType>::Test(
+                   static_cast<BigType>(static_cast<L>(lhs)),
+                   static_cast<BigType>(static_cast<R>(rhs)))
+             // Let the template functions figure it out for mixed types.
+             : C<L, R>::Test(lhs, rhs);
+}
+
+template <typename Dst, typename Src>
+constexpr bool IsMaxInRangeForNumericType() {
+  return IsGreaterOrEqual<Dst, Src>::Test(std::numeric_limits<Dst>::max(),
+                                          std::numeric_limits<Src>::max());
+}
+
+template <typename Dst, typename Src>
+constexpr bool IsMinInRangeForNumericType() {
+  return IsLessOrEqual<Dst, Src>::Test(std::numeric_limits<Dst>::lowest(),
+                                       std::numeric_limits<Src>::lowest());
+}
+
+template <typename Dst, typename Src>
+constexpr Dst CommonMax() {
+  return !IsMaxInRangeForNumericType<Dst, Src>()
+             ? Dst(std::numeric_limits<Dst>::max())
+             : Dst(std::numeric_limits<Src>::max());
+}
+
+template <typename Dst, typename Src>
+constexpr Dst CommonMin() {
+  return !IsMinInRangeForNumericType<Dst, Src>()
+             ? Dst(std::numeric_limits<Dst>::lowest())
+             : Dst(std::numeric_limits<Src>::lowest());
+}
+
+// This is a wrapper to generate return the max or min for a supplied type.
+// If the argument is false, the returned value is the maximum. If true the
+// returned value is the minimum.
+template <typename Dst, typename Src = Dst>
+constexpr Dst CommonMaxOrMin(bool is_min) {
+  return is_min ? CommonMin<Dst, Src>() : CommonMax<Dst, Src>();
+}
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
diff --git a/base/numerics/safe_math.h b/base/numerics/safe_math.h
new file mode 100644
index 0000000..e30be90
--- /dev/null
+++ b/base/numerics/safe_math.h
@@ -0,0 +1,12 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_SAFE_MATH_H_
+#define BASE_NUMERICS_SAFE_MATH_H_
+
+#include "base/numerics/checked_math.h"
+#include "base/numerics/clamped_math.h"
+#include "base/numerics/safe_conversions.h"
+
+#endif  // BASE_NUMERICS_SAFE_MATH_H_
diff --git a/base/numerics/safe_math_arm_impl.h b/base/numerics/safe_math_arm_impl.h
new file mode 100644
index 0000000..a7cda1b
--- /dev/null
+++ b/base/numerics/safe_math_arm_impl.h
@@ -0,0 +1,122 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_SAFE_MATH_ARM_IMPL_H_
+#define BASE_NUMERICS_SAFE_MATH_ARM_IMPL_H_
+
+#include <cassert>
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/safe_conversions.h"
+
+namespace base {
+namespace internal {
+
+template <typename T, typename U>
+struct CheckedMulFastAsmOp {
+  static const bool is_supported =
+      FastIntegerArithmeticPromotion<T, U>::is_contained;
+
+  // The following is much more efficient than the Clang and GCC builtins for
+  // performing overflow-checked multiplication when a twice wider type is
+  // available. The below compiles down to 2-3 instructions, depending on the
+  // width of the types in use.
+  // As an example, an int32_t multiply compiles to:
+  //    smull   r0, r1, r0, r1
+  //    cmp     r1, r1, asr #31
+  // And an int16_t multiply compiles to:
+  //    smulbb  r1, r1, r0
+  //    asr     r2, r1, #16
+  //    cmp     r2, r1, asr #15
+  template <typename V>
+  __attribute__((always_inline)) static bool Do(T x, U y, V* result) {
+    using Promotion = typename FastIntegerArithmeticPromotion<T, U>::type;
+    Promotion presult;
+
+    presult = static_cast<Promotion>(x) * static_cast<Promotion>(y);
+    *result = static_cast<V>(presult);
+    return IsValueInRangeForNumericType<V>(presult);
+  }
+};
+
+template <typename T, typename U>
+struct ClampedAddFastAsmOp {
+  static const bool is_supported =
+      BigEnoughPromotion<T, U>::is_contained &&
+      IsTypeInRangeForNumericType<
+          int32_t,
+          typename BigEnoughPromotion<T, U>::type>::value;
+
+  template <typename V>
+  __attribute__((always_inline)) static V Do(T x, U y) {
+    // This will get promoted to an int, so let the compiler do whatever is
+    // clever and rely on the saturated cast to bounds check.
+    if (IsIntegerArithmeticSafe<int, T, U>::value)
+      return saturated_cast<V>(x + y);
+
+    int32_t result;
+    int32_t x_i32 = x;
+    int32_t y_i32 = y;
+
+    asm("qadd %[result], %[first], %[second]"
+        : [result] "=r"(result)
+        : [first] "r"(x_i32), [second] "r"(y_i32));
+    return saturated_cast<V>(result);
+  }
+};
+
+template <typename T, typename U>
+struct ClampedSubFastAsmOp {
+  static const bool is_supported =
+      BigEnoughPromotion<T, U>::is_contained &&
+      IsTypeInRangeForNumericType<
+          int32_t,
+          typename BigEnoughPromotion<T, U>::type>::value;
+
+  template <typename V>
+  __attribute__((always_inline)) static V Do(T x, U y) {
+    // This will get promoted to an int, so let the compiler do whatever is
+    // clever and rely on the saturated cast to bounds check.
+    if (IsIntegerArithmeticSafe<int, T, U>::value)
+      return saturated_cast<V>(x - y);
+
+    int32_t result;
+    int32_t x_i32 = x;
+    int32_t y_i32 = y;
+
+    asm("qsub %[result], %[first], %[second]"
+        : [result] "=r"(result)
+        : [first] "r"(x_i32), [second] "r"(y_i32));
+    return saturated_cast<V>(result);
+  }
+};
+
+template <typename T, typename U>
+struct ClampedMulFastAsmOp {
+  static const bool is_supported = CheckedMulFastAsmOp<T, U>::is_supported;
+
+  template <typename V>
+  __attribute__((always_inline)) static V Do(T x, U y) {
+    // Use the CheckedMulFastAsmOp for full-width 32-bit values, because
+    // it's fewer instructions than promoting and then saturating.
+    if (!IsIntegerArithmeticSafe<int32_t, T, U>::value &&
+        !IsIntegerArithmeticSafe<uint32_t, T, U>::value) {
+      V result;
+      if (CheckedMulFastAsmOp<T, U>::Do(x, y, &result))
+        return result;
+      return CommonMaxOrMin<V>(IsValueNegative(x) ^ IsValueNegative(y));
+    }
+
+    assert((FastIntegerArithmeticPromotion<T, U>::is_contained));
+    using Promotion = typename FastIntegerArithmeticPromotion<T, U>::type;
+    return saturated_cast<V>(static_cast<Promotion>(x) *
+                             static_cast<Promotion>(y));
+  }
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_NUMERICS_SAFE_MATH_ARM_IMPL_H_
diff --git a/base/numerics/safe_math_clang_gcc_impl.h b/base/numerics/safe_math_clang_gcc_impl.h
new file mode 100644
index 0000000..1760338
--- /dev/null
+++ b/base/numerics/safe_math_clang_gcc_impl.h
@@ -0,0 +1,157 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_SAFE_MATH_CLANG_GCC_IMPL_H_
+#define BASE_NUMERICS_SAFE_MATH_CLANG_GCC_IMPL_H_
+
+#include <cassert>
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/safe_conversions.h"
+
+#if !defined(__native_client__) && (defined(__ARMEL__) || defined(__arch64__))
+#include "base/numerics/safe_math_arm_impl.h"
+#define BASE_HAS_ASSEMBLER_SAFE_MATH (1)
+#else
+#define BASE_HAS_ASSEMBLER_SAFE_MATH (0)
+#endif
+
+namespace base {
+namespace internal {
+
+// These are the non-functioning boilerplate implementations of the optimized
+// safe math routines.
+#if !BASE_HAS_ASSEMBLER_SAFE_MATH
+template <typename T, typename U>
+struct CheckedMulFastAsmOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr bool Do(T, U, V*) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<bool>();
+  }
+};
+
+template <typename T, typename U>
+struct ClampedAddFastAsmOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr V Do(T, U) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<V>();
+  }
+};
+
+template <typename T, typename U>
+struct ClampedSubFastAsmOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr V Do(T, U) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<V>();
+  }
+};
+
+template <typename T, typename U>
+struct ClampedMulFastAsmOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr V Do(T, U) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<V>();
+  }
+};
+#endif  // BASE_HAS_ASSEMBLER_SAFE_MATH
+#undef BASE_HAS_ASSEMBLER_SAFE_MATH
+
+template <typename T, typename U>
+struct CheckedAddFastOp {
+  static const bool is_supported = true;
+  template <typename V>
+  __attribute__((always_inline)) static constexpr bool Do(T x, U y, V* result) {
+    return !__builtin_add_overflow(x, y, result);
+  }
+};
+
+template <typename T, typename U>
+struct CheckedSubFastOp {
+  static const bool is_supported = true;
+  template <typename V>
+  __attribute__((always_inline)) static constexpr bool Do(T x, U y, V* result) {
+    return !__builtin_sub_overflow(x, y, result);
+  }
+};
+
+template <typename T, typename U>
+struct CheckedMulFastOp {
+#if defined(__clang__)
+  // TODO(jschuh): Get the Clang runtime library issues sorted out so we can
+  // support full-width, mixed-sign multiply builtins.
+  // https://crbug.com/613003
+  // We can support intptr_t, uintptr_t, or a smaller common type.
+  static const bool is_supported =
+      (IsTypeInRangeForNumericType<intptr_t, T>::value &&
+       IsTypeInRangeForNumericType<intptr_t, U>::value) ||
+      (IsTypeInRangeForNumericType<uintptr_t, T>::value &&
+       IsTypeInRangeForNumericType<uintptr_t, U>::value);
+#else
+  static const bool is_supported = true;
+#endif
+  template <typename V>
+  __attribute__((always_inline)) static constexpr bool Do(T x, U y, V* result) {
+    return CheckedMulFastAsmOp<T, U>::is_supported
+               ? CheckedMulFastAsmOp<T, U>::Do(x, y, result)
+               : !__builtin_mul_overflow(x, y, result);
+  }
+};
+
+template <typename T, typename U>
+struct ClampedAddFastOp {
+  static const bool is_supported = ClampedAddFastAsmOp<T, U>::is_supported;
+  template <typename V>
+  __attribute__((always_inline)) static V Do(T x, U y) {
+    return ClampedAddFastAsmOp<T, U>::template Do<V>(x, y);
+  }
+};
+
+template <typename T, typename U>
+struct ClampedSubFastOp {
+  static const bool is_supported = ClampedSubFastAsmOp<T, U>::is_supported;
+  template <typename V>
+  __attribute__((always_inline)) static V Do(T x, U y) {
+    return ClampedSubFastAsmOp<T, U>::template Do<V>(x, y);
+  }
+};
+
+template <typename T, typename U>
+struct ClampedMulFastOp {
+  static const bool is_supported = ClampedMulFastAsmOp<T, U>::is_supported;
+  template <typename V>
+  __attribute__((always_inline)) static V Do(T x, U y) {
+    return ClampedMulFastAsmOp<T, U>::template Do<V>(x, y);
+  }
+};
+
+template <typename T>
+struct ClampedNegFastOp {
+  static const bool is_supported = std::is_signed<T>::value;
+  __attribute__((always_inline)) static T Do(T value) {
+    // Use this when there is no assembler path available.
+    if (!ClampedSubFastAsmOp<T, T>::is_supported) {
+      T result;
+      return !__builtin_sub_overflow(T(0), value, &result)
+                 ? result
+                 : std::numeric_limits<T>::max();
+    }
+
+    // Fallback to the normal subtraction path.
+    return ClampedSubFastOp<T, T>::template Do<T>(T(0), value);
+  }
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_NUMERICS_SAFE_MATH_CLANG_GCC_IMPL_H_
diff --git a/base/numerics/safe_math_shared_impl.h b/base/numerics/safe_math_shared_impl.h
new file mode 100644
index 0000000..583c487
--- /dev/null
+++ b/base/numerics/safe_math_shared_impl.h
@@ -0,0 +1,237 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_
+#define BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <cassert>
+#include <climits>
+#include <cmath>
+#include <cstdlib>
+#include <limits>
+#include <type_traits>
+
+#include "base/numerics/safe_conversions.h"
+
+// Where available use builtin math overflow support on Clang and GCC.
+#if !defined(__native_client__) &&                         \
+    ((defined(__clang__) &&                                \
+      ((__clang_major__ > 3) ||                            \
+       (__clang_major__ == 3 && __clang_minor__ >= 4))) || \
+     (defined(__GNUC__) && __GNUC__ >= 5))
+#include "base/numerics/safe_math_clang_gcc_impl.h"
+#define BASE_HAS_OPTIMIZED_SAFE_MATH (1)
+#else
+#define BASE_HAS_OPTIMIZED_SAFE_MATH (0)
+#endif
+
+namespace base {
+namespace internal {
+
+// These are the non-functioning boilerplate implementations of the optimized
+// safe math routines.
+#if !BASE_HAS_OPTIMIZED_SAFE_MATH
+template <typename T, typename U>
+struct CheckedAddFastOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr bool Do(T, U, V*) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<bool>();
+  }
+};
+
+template <typename T, typename U>
+struct CheckedSubFastOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr bool Do(T, U, V*) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<bool>();
+  }
+};
+
+template <typename T, typename U>
+struct CheckedMulFastOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr bool Do(T, U, V*) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<bool>();
+  }
+};
+
+template <typename T, typename U>
+struct ClampedAddFastOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr V Do(T, U) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<V>();
+  }
+};
+
+template <typename T, typename U>
+struct ClampedSubFastOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr V Do(T, U) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<V>();
+  }
+};
+
+template <typename T, typename U>
+struct ClampedMulFastOp {
+  static const bool is_supported = false;
+  template <typename V>
+  static constexpr V Do(T, U) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<V>();
+  }
+};
+
+template <typename T>
+struct ClampedNegFastOp {
+  static const bool is_supported = false;
+  static constexpr T Do(T) {
+    // Force a compile failure if instantiated.
+    return CheckOnFailure::template HandleFailure<T>();
+  }
+};
+#endif  // BASE_HAS_OPTIMIZED_SAFE_MATH
+#undef BASE_HAS_OPTIMIZED_SAFE_MATH
+
+// This is used for UnsignedAbs, where we need to support floating-point
+// template instantiations even though we don't actually support the operations.
+// However, there is no corresponding implementation of e.g. SafeUnsignedAbs,
+// so the float versions will not compile.
+template <typename Numeric,
+          bool IsInteger = std::is_integral<Numeric>::value,
+          bool IsFloat = std::is_floating_point<Numeric>::value>
+struct UnsignedOrFloatForSize;
+
+template <typename Numeric>
+struct UnsignedOrFloatForSize<Numeric, true, false> {
+  using type = typename std::make_unsigned<Numeric>::type;
+};
+
+template <typename Numeric>
+struct UnsignedOrFloatForSize<Numeric, false, true> {
+  using type = Numeric;
+};
+
+// Wrap the unary operations to allow SFINAE when instantiating integrals versus
+// floating points. These don't perform any overflow checking. Rather, they
+// exhibit well-defined overflow semantics and rely on the caller to detect
+// if an overflow occured.
+
+template <typename T,
+          typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
+constexpr T NegateWrapper(T value) {
+  using UnsignedT = typename std::make_unsigned<T>::type;
+  // This will compile to a NEG on Intel, and is normal negation on ARM.
+  return static_cast<T>(UnsignedT(0) - static_cast<UnsignedT>(value));
+}
+
+template <
+    typename T,
+    typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr>
+constexpr T NegateWrapper(T value) {
+  return -value;
+}
+
+template <typename T,
+          typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
+constexpr typename std::make_unsigned<T>::type InvertWrapper(T value) {
+  return ~value;
+}
+
+template <typename T,
+          typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
+constexpr T AbsWrapper(T value) {
+  return static_cast<T>(SafeUnsignedAbs(value));
+}
+
+template <
+    typename T,
+    typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr>
+constexpr T AbsWrapper(T value) {
+  return value < 0 ? -value : value;
+}
+
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R>
+struct MathWrapper {
+  using math = M<typename UnderlyingType<L>::type,
+                 typename UnderlyingType<R>::type,
+                 void>;
+  using type = typename math::result_type;
+};
+
+// These variadic templates work out the return types.
+// TODO(jschuh): Rip all this out once we have C++14 non-trailing auto support.
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R,
+          typename... Args>
+struct ResultType;
+
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R>
+struct ResultType<M, L, R> {
+  using type = typename MathWrapper<M, L, R>::type;
+};
+
+template <template <typename, typename, typename> class M,
+          typename L,
+          typename R,
+          typename... Args>
+struct ResultType {
+  using type =
+      typename ResultType<M, typename ResultType<M, L, R>::type, Args...>::type;
+};
+
+// The following macros are just boilerplate for the standard arithmetic
+// operator overloads and variadic function templates. A macro isn't the nicest
+// solution, but it beats rewriting these over and over again.
+#define BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME)       \
+  template <typename L, typename R, typename... Args>                   \
+  constexpr CLASS##Numeric<                                             \
+      typename ResultType<CLASS##OP_NAME##Op, L, R, Args...>::type>     \
+      CL_ABBR##OP_NAME(const L lhs, const R rhs, const Args... args) {  \
+    return CL_ABBR##MathOp<CLASS##OP_NAME##Op, L, R, Args...>(lhs, rhs, \
+                                                              args...); \
+  }
+
+#define BASE_NUMERIC_ARITHMETIC_OPERATORS(CLASS, CL_ABBR, OP_NAME, OP, CMP_OP) \
+  /* Binary arithmetic operator for all CLASS##Numeric operations. */          \
+  template <typename L, typename R,                                            \
+            typename std::enable_if<Is##CLASS##Op<L, R>::value>::type* =       \
+                nullptr>                                                       \
+  constexpr CLASS##Numeric<                                                    \
+      typename MathWrapper<CLASS##OP_NAME##Op, L, R>::type>                    \
+  operator OP(const L lhs, const R rhs) {                                      \
+    return decltype(lhs OP rhs)::template MathOp<CLASS##OP_NAME##Op>(lhs,      \
+                                                                     rhs);     \
+  }                                                                            \
+  /* Assignment arithmetic operator implementation from CLASS##Numeric. */     \
+  template <typename L>                                                        \
+  template <typename R>                                                        \
+  constexpr CLASS##Numeric<L>& CLASS##Numeric<L>::operator CMP_OP(             \
+      const R rhs) {                                                           \
+    return MathOp<CLASS##OP_NAME##Op>(rhs);                                    \
+  }                                                                            \
+  /* Variadic arithmetic functions that return CLASS##Numeric. */              \
+  BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME)
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_