diff --git a/base/json/string_escape.cc b/base/json/string_escape.cc
new file mode 100644
index 0000000..471a9d3
--- /dev/null
+++ b/base/json/string_escape.cc
@@ -0,0 +1,167 @@
+// Copyright (c) 2006-2008 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.
+
+#include "base/json/string_escape.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <limits>
+#include <string>
+
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversion_utils.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/third_party/icu/icu_utf.h"
+
+namespace base {
+
+namespace {
+
+// Format string for printing a \uXXXX escape sequence.
+const char kU16EscapeFormat[] = "\\u%04X";
+
+// The code point to output for an invalid input code unit.
+const uint32_t kReplacementCodePoint = 0xFFFD;
+
+// Used below in EscapeSpecialCodePoint().
+static_assert('<' == 0x3C, "less than sign must be 0x3c");
+
+// Try to escape the |code_point| if it is a known special character. If
+// successful, returns true and appends the escape sequence to |dest|. This
+// isn't required by the spec, but it's more readable by humans.
+bool EscapeSpecialCodePoint(uint32_t code_point, std::string* dest) {
+  // WARNING: if you add a new case here, you need to update the reader as well.
+  // Note: \v is in the reader, but not here since the JSON spec doesn't
+  // allow it.
+  switch (code_point) {
+    case '\b':
+      dest->append("\\b");
+      break;
+    case '\f':
+      dest->append("\\f");
+      break;
+    case '\n':
+      dest->append("\\n");
+      break;
+    case '\r':
+      dest->append("\\r");
+      break;
+    case '\t':
+      dest->append("\\t");
+      break;
+    case '\\':
+      dest->append("\\\\");
+      break;
+    case '"':
+      dest->append("\\\"");
+      break;
+    // Escape < to prevent script execution; escaping > is not necessary and
+    // not doing so save a few bytes.
+    case '<':
+      dest->append("\\u003C");
+      break;
+    // Escape the "Line Separator" and "Paragraph Separator" characters, since
+    // they should be treated like a new line \r or \n.
+    case 0x2028:
+      dest->append("\\u2028");
+      break;
+    case 0x2029:
+      dest->append("\\u2029");
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+
+template <typename S>
+bool EscapeJSONStringImpl(const S& str, bool put_in_quotes, std::string* dest) {
+  bool did_replacement = false;
+
+  if (put_in_quotes)
+    dest->push_back('"');
+
+  // Casting is necessary because ICU uses int32_t. Try and do so safely.
+  CHECK_LE(str.length(),
+           static_cast<size_t>(std::numeric_limits<int32_t>::max()));
+  const int32_t length = static_cast<int32_t>(str.length());
+
+  for (int32_t i = 0; i < length; ++i) {
+    uint32_t code_point;
+    if (!ReadUnicodeCharacter(str.data(), length, &i, &code_point) ||
+        code_point == static_cast<decltype(code_point)>(CBU_SENTINEL) ||
+        !IsValidCharacter(code_point)) {
+      code_point = kReplacementCodePoint;
+      did_replacement = true;
+    }
+
+    if (EscapeSpecialCodePoint(code_point, dest))
+      continue;
+
+    // Escape non-printing characters.
+    if (code_point < 32)
+      base::StringAppendF(dest, kU16EscapeFormat, code_point);
+    else
+      WriteUnicodeCharacter(code_point, dest);
+  }
+
+  if (put_in_quotes)
+    dest->push_back('"');
+
+  return !did_replacement;
+}
+
+}  // namespace
+
+bool EscapeJSONString(StringPiece str, bool put_in_quotes, std::string* dest) {
+  return EscapeJSONStringImpl(str, put_in_quotes, dest);
+}
+
+bool EscapeJSONString(StringPiece16 str,
+                      bool put_in_quotes,
+                      std::string* dest) {
+  return EscapeJSONStringImpl(str, put_in_quotes, dest);
+}
+
+std::string GetQuotedJSONString(StringPiece str) {
+  std::string dest;
+  bool ok = EscapeJSONStringImpl(str, true, &dest);
+  DCHECK(ok);
+  return dest;
+}
+
+std::string GetQuotedJSONString(StringPiece16 str) {
+  std::string dest;
+  bool ok = EscapeJSONStringImpl(str, true, &dest);
+  DCHECK(ok);
+  return dest;
+}
+
+std::string EscapeBytesAsInvalidJSONString(StringPiece str,
+                                           bool put_in_quotes) {
+  std::string dest;
+
+  if (put_in_quotes)
+    dest.push_back('"');
+
+  for (StringPiece::const_iterator it = str.begin(); it != str.end(); ++it) {
+    unsigned char c = *it;
+    if (EscapeSpecialCodePoint(c, &dest))
+      continue;
+
+    if (c < 32 || c > 126)
+      base::StringAppendF(&dest, kU16EscapeFormat, c);
+    else
+      dest.push_back(*it);
+  }
+
+  if (put_in_quotes)
+    dest.push_back('"');
+
+  return dest;
+}
+
+}  // namespace base