diff --git a/README.md b/README.md
index 486b14d..498b017 100644
--- a/README.md
+++ b/README.md
@@ -7,5 +7,5 @@
 
     git clone https://gn.googlesource.com/gn
     cd gn
-    build/gen.py
+    python build/gen.py
     ninja -C out
diff --git a/base/metrics/field_trial.cc b/base/metrics/field_trial.cc
index ed4f147..25f21ca 100644
--- a/base/metrics/field_trial.cc
+++ b/base/metrics/field_trial.cc
@@ -1229,7 +1229,8 @@
 #if defined(OS_FUCHSIA)
   zx_handle_t handle = static_cast<zx_handle_t>(field_trial_handle);
 #elif defined(OS_WIN)
-  HANDLE handle = reinterpret_cast<HANDLE>(field_trial_handle);
+  HANDLE handle =
+      reinterpret_cast<HANDLE>(static_cast<uintptr_t>(field_trial_handle));
   if (base::IsCurrentProcessElevated()) {
     // base::LaunchElevatedProcess doesn't have a way to duplicate the handle,
     // but this process can since by definition it's not sandboxed.
diff --git a/base/task_scheduler/scheduler_worker_pool_impl.cc b/base/task_scheduler/scheduler_worker_pool_impl.cc
index b309bbd..0e0c107 100644
--- a/base/task_scheduler/scheduler_worker_pool_impl.cc
+++ b/base/task_scheduler/scheduler_worker_pool_impl.cc
@@ -31,7 +31,6 @@
 #if defined(OS_WIN)
 #include "base/win/scoped_com_initializer.h"
 #include "base/win/scoped_windows_thread_environment.h"
-#include "base/win/scoped_winrt_initializer.h"
 #include "base/win/windows_version.h"
 #endif  // defined(OS_WIN)
 
@@ -152,10 +151,6 @@
   // returned a non-empty sequence and DidRunTask() hasn't been called yet).
   bool is_running_task_ = false;
 
-#if defined(OS_WIN)
-  std::unique_ptr<win::ScopedWindowsThreadEnvironment> win_thread_environment_;
-#endif  // defined(OS_WIN)
-
   // Verifies that specific calls are always made from the worker thread.
   THREAD_CHECKER(worker_thread_checker_);
 
@@ -405,18 +400,6 @@
 #endif
   }
 
-#if defined(OS_WIN)
-  if (outer_->worker_environment_ == WorkerEnvironment::COM_MTA) {
-    if (win::GetVersion() >= win::VERSION_WIN8) {
-      win_thread_environment_ = std::make_unique<win::ScopedWinrtInitializer>();
-    } else {
-      win_thread_environment_ = std::make_unique<win::ScopedCOMInitializer>(
-          win::ScopedCOMInitializer::kMTA);
-    }
-    DCHECK(win_thread_environment_->Succeeded());
-  }
-#endif  // defined(OS_WIN)
-
   DCHECK_EQ(num_tasks_since_last_wait_, 0U);
 
   PlatformThread::SetName(
@@ -588,10 +571,6 @@
     }
   }
 #endif
-
-#if defined(OS_WIN)
-  win_thread_environment_.reset();
-#endif  // defined(OS_WIN)
 }
 
 void SchedulerWorkerPoolImpl::SchedulerWorkerDelegateImpl::
diff --git a/base/task_scheduler/task_tracker.cc b/base/task_scheduler/task_tracker.cc
index ab46b9e..5c98b5c 100644
--- a/base/task_scheduler/task_tracker.cc
+++ b/base/task_scheduler/task_tracker.cc
@@ -454,15 +454,6 @@
 
   DCHECK(latency_histogram_type == LatencyHistogramType::TASK_LATENCY ||
          latency_histogram_type == LatencyHistogramType::HEARTBEAT_LATENCY);
-  auto& histograms =
-      latency_histogram_type == LatencyHistogramType::TASK_LATENCY
-          ? task_latency_histograms_
-          : heartbeat_latency_histograms_;
-  histograms[static_cast<int>(task_traits.priority())]
-            [task_traits.may_block() || task_traits.with_base_sync_primitives()
-                 ? 1
-                 : 0]
-                ->AddTimeMicrosecondsGranularity(task_latency);
 }
 
 void TaskTracker::RunOrSkipTask(Task task,
diff --git a/base/trace_event/trace_event_etw_export_win.cc b/base/trace_event/trace_event_etw_export_win.cc
deleted file mode 100644
index 993a222..0000000
--- a/base/trace_event/trace_event_etw_export_win.cc
+++ /dev/null
@@ -1,380 +0,0 @@
-// Copyright 2015 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/trace_event/trace_event_etw_export_win.h"
-
-#include <stddef.h>
-
-#include "base/command_line.h"
-#include "base/logging.h"
-#include "base/memory/singleton.h"
-#include "base/strings/string_tokenizer.h"
-#include "base/strings/utf_string_conversions.h"
-#include "base/threading/platform_thread.h"
-#include "base/trace_event/trace_event.h"
-#include "base/trace_event/trace_event_impl.h"
-
-#include <windows.h>
-
-// The GetProcAddress technique is borrowed from
-// https://github.com/google/UIforETW/tree/master/ETWProviders
-//
-// EVNTAPI is used in evntprov.h which is included by chrome_events_win.h.
-// We define EVNTAPI without the DECLSPEC_IMPORT specifier so that we can
-// implement these functions locally instead of using the import library, and
-// can therefore still run on Windows XP.
-#define EVNTAPI __stdcall
-// Include the event register/write/unregister macros compiled from the manifest
-// file. Note that this includes evntprov.h which requires a Vista+ Windows SDK.
-//
-// In SHARED_INTERMEDIATE_DIR.
-#include "base/trace_event/etw_manifest/chrome_events_win.h"  // NOLINT
-
-namespace {
-// |kFilteredEventGroupNames| contains the event categories that can be
-// exported individually. These categories can be enabled by passing the correct
-// keyword when starting the trace. A keyword is a 64-bit flag and we attribute
-// one bit per category. We can therefore enable a particular category by
-// setting its corresponding bit in the keyword. For events that are not present
-// in |kFilteredEventGroupNames|, we have two bits that control their
-// behaviour. When bit 61 is enabled, any event that is not disabled by default
-// (ie. doesn't start with disabled-by-default-) will be exported. Likewise,
-// when bit 62 is enabled, any event that is disabled by default will be
-// exported.
-//
-// Note that bit 63 (MSB) must always be set, otherwise tracing will be disabled
-// by ETW. Therefore, the keyword will always be greater than
-// 0x8000000000000000.
-//
-// Examples of passing keywords to the provider using xperf:
-// # This exports "benchmark" and "cc" events
-// xperf -start chrome -on Chrome:0x8000000000000009
-//
-// # This exports "gpu", "netlog" and all other events that are not disabled by
-// # default
-// xperf -start chrome -on Chrome:0xA0000000000000A0
-//
-// More info about starting a trace and keyword can be obtained by using the
-// help section of xperf (xperf -help start). Note that xperf documentation
-// refers to keywords as flags and there are two ways to enable them, using
-// group names or the hex representation. We only support the latter. Also, we
-// ignore the level.
-const char* const kFilteredEventGroupNames[] = {
-    "benchmark",                                       // 0x1
-    "blink",                                           // 0x2
-    "browser",                                         // 0x4
-    "cc",                                              // 0x8
-    "evdev",                                           // 0x10
-    "gpu",                                             // 0x20
-    "input",                                           // 0x40
-    "netlog",                                          // 0x80
-    "sequence_manager",                                // 0x100
-    "toplevel",                                        // 0x200
-    "v8",                                              // 0x400
-    "disabled-by-default-cc.debug",                    // 0x800
-    "disabled-by-default-cc.debug.picture",            // 0x1000
-    "disabled-by-default-toplevel.flow",               // 0x2000
-    "startup"};                                        // 0x4000
-const char kOtherEventsGroupName[] = "__OTHER_EVENTS";  // 0x2000000000000000
-const char kDisabledOtherEventsGroupName[] =
-    "__DISABLED_OTHER_EVENTS";  // 0x4000000000000000
-const uint64_t kOtherEventsKeywordBit = 1ULL << 61;
-const uint64_t kDisabledOtherEventsKeywordBit = 1ULL << 62;
-const size_t kNumberOfCategories = ARRAYSIZE(kFilteredEventGroupNames) + 2U;
-
-}  // namespace
-
-namespace base {
-namespace trace_event {
-
-// This object will be created by each process. It's a background (low-priority)
-// thread that will monitor the ETW keyword for any changes.
-class TraceEventETWExport::ETWKeywordUpdateThread
-    : public PlatformThread::Delegate {
- public:
-  ETWKeywordUpdateThread() {}
-  ~ETWKeywordUpdateThread() override {}
-
-  // Implementation of PlatformThread::Delegate:
-  void ThreadMain() override {
-    PlatformThread::SetName("ETW Keyword Update Thread");
-    TimeDelta sleep_time = TimeDelta::FromMilliseconds(kUpdateTimerDelayMs);
-    while (1) {
-      PlatformThread::Sleep(sleep_time);
-      trace_event::TraceEventETWExport::UpdateETWKeyword();
-    }
-  }
-
- private:
-  // Time between checks for ETW keyword changes (in milliseconds).
-  unsigned int kUpdateTimerDelayMs = 1000;
-};
-
-
-TraceEventETWExport::TraceEventETWExport()
-    : etw_export_enabled_(false), etw_match_any_keyword_(0ULL) {
-  // Register the ETW provider. If registration fails then the event logging
-  // calls will fail.
-  EventRegisterChrome();
-
-  // Make sure to initialize the map with all the group names. Subsequent
-  // modifications will be made by the background thread and only affect the
-  // values of the keys (no key addition/deletion). Therefore, the map does not
-  // require a lock for access.
-  for (size_t i = 0; i < ARRAYSIZE(kFilteredEventGroupNames); i++)
-    categories_status_[kFilteredEventGroupNames[i]] = false;
-  categories_status_[kOtherEventsGroupName] = false;
-  categories_status_[kDisabledOtherEventsGroupName] = false;
-  DCHECK_EQ(kNumberOfCategories, categories_status_.size());
-}
-
-TraceEventETWExport::~TraceEventETWExport() {
-  EventUnregisterChrome();
-}
-
-// static
-TraceEventETWExport* TraceEventETWExport::GetInstance() {
-  return Singleton<TraceEventETWExport,
-                   StaticMemorySingletonTraits<TraceEventETWExport>>::get();
-}
-
-// static
-void TraceEventETWExport::EnableETWExport() {
-  auto* instance = GetInstance();
-  if (instance && !instance->etw_export_enabled_) {
-    instance->etw_export_enabled_ = true;
-    // Sync the enabled categories with ETW by calling UpdateEnabledCategories()
-    // that checks the keyword. Then create a thread that will call that same
-    // function periodically, to make sure we stay in sync.
-    instance->UpdateEnabledCategories();
-    if (instance->keyword_update_thread_handle_.is_null()) {
-      instance->keyword_update_thread_.reset(new ETWKeywordUpdateThread);
-      PlatformThread::CreateWithPriority(
-          0, instance->keyword_update_thread_.get(),
-          &instance->keyword_update_thread_handle_, ThreadPriority::BACKGROUND);
-    }
-  }
-}
-
-// static
-void TraceEventETWExport::DisableETWExport() {
-  auto* instance = GetInstance();
-  if (instance && instance->etw_export_enabled_)
-    instance->etw_export_enabled_ = false;
-}
-
-// static
-bool TraceEventETWExport::IsETWExportEnabled() {
-  auto* instance = GetInstance();
-  return (instance && instance->etw_export_enabled_);
-}
-
-// static
-void TraceEventETWExport::AddEvent(
-    char phase,
-    const unsigned char* category_group_enabled,
-    const char* name,
-    unsigned long long id,
-    int num_args,
-    const char* const* arg_names,
-    const unsigned char* arg_types,
-    const unsigned long long* arg_values,
-    const std::unique_ptr<ConvertableToTraceFormat>* convertable_values) {
-  // We bail early in case exporting is disabled or no consumer is listening.
-  auto* instance = GetInstance();
-  if (!instance || !instance->etw_export_enabled_ || !EventEnabledChromeEvent())
-    return;
-
-  const char* phase_string = nullptr;
-  // Space to store the phase identifier and null-terminator, when needed.
-  char phase_buffer[2];
-  switch (phase) {
-    case TRACE_EVENT_PHASE_BEGIN:
-      phase_string = "Begin";
-      break;
-    case TRACE_EVENT_PHASE_END:
-      phase_string = "End";
-      break;
-    case TRACE_EVENT_PHASE_COMPLETE:
-      phase_string = "Complete";
-      break;
-    case TRACE_EVENT_PHASE_INSTANT:
-      phase_string = "Instant";
-      break;
-    case TRACE_EVENT_PHASE_ASYNC_BEGIN:
-      phase_string = "Async Begin";
-      break;
-    case TRACE_EVENT_PHASE_ASYNC_STEP_INTO:
-      phase_string = "Async Step Into";
-      break;
-    case TRACE_EVENT_PHASE_ASYNC_STEP_PAST:
-      phase_string = "Async Step Past";
-      break;
-    case TRACE_EVENT_PHASE_ASYNC_END:
-      phase_string = "Async End";
-      break;
-    case TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN:
-      phase_string = "Nestable Async Begin";
-      break;
-    case TRACE_EVENT_PHASE_NESTABLE_ASYNC_END:
-      phase_string = "Nestable Async End";
-      break;
-    case TRACE_EVENT_PHASE_NESTABLE_ASYNC_INSTANT:
-      phase_string = "Nestable Async Instant";
-      break;
-    case TRACE_EVENT_PHASE_FLOW_BEGIN:
-      phase_string = "Phase Flow Begin";
-      break;
-    case TRACE_EVENT_PHASE_FLOW_STEP:
-      phase_string = "Phase Flow Step";
-      break;
-    case TRACE_EVENT_PHASE_FLOW_END:
-      phase_string = "Phase Flow End";
-      break;
-    case TRACE_EVENT_PHASE_METADATA:
-      phase_string = "Phase Metadata";
-      break;
-    case TRACE_EVENT_PHASE_COUNTER:
-      phase_string = "Phase Counter";
-      break;
-    case TRACE_EVENT_PHASE_SAMPLE:
-      phase_string = "Phase Sample";
-      break;
-    case TRACE_EVENT_PHASE_CREATE_OBJECT:
-      phase_string = "Phase Create Object";
-      break;
-    case TRACE_EVENT_PHASE_SNAPSHOT_OBJECT:
-      phase_string = "Phase Snapshot Object";
-      break;
-    case TRACE_EVENT_PHASE_DELETE_OBJECT:
-      phase_string = "Phase Delete Object";
-      break;
-    default:
-      phase_buffer[0] = phase;
-      phase_buffer[1] = 0;
-      phase_string = phase_buffer;
-      break;
-  }
-
-  std::string arg_values_string[3];
-  for (int i = 0; i < num_args; i++) {
-    if (arg_types[i] == TRACE_VALUE_TYPE_CONVERTABLE) {
-      // Temporarily do nothing here. This function consumes 1/3 to 1/2 of
-      // *total* process CPU time when ETW tracing, and many of the strings
-      // created exceed WPA's 4094 byte limit and are shown as:
-      // "Unable to parse data". See crbug.com/488257
-      // convertable_values[i]->AppendAsTraceFormat(arg_values_string + i);
-    } else {
-      TraceEvent::TraceValue trace_event;
-      trace_event.as_uint = arg_values[i];
-      TraceEvent::AppendValueAsJSON(arg_types[i], trace_event,
-                                    arg_values_string + i);
-    }
-  }
-
-  EventWriteChromeEvent(
-      name, phase_string, num_args > 0 ? arg_names[0] : "",
-      arg_values_string[0].c_str(), num_args > 1 ? arg_names[1] : "",
-      arg_values_string[1].c_str(), num_args > 2 ? arg_names[2] : "",
-      arg_values_string[2].c_str());
-}
-
-// static
-void TraceEventETWExport::AddCompleteEndEvent(const char* name) {
-  auto* instance = GetInstance();
-  if (!instance || !instance->etw_export_enabled_ || !EventEnabledChromeEvent())
-    return;
-
-  EventWriteChromeEvent(name, "Complete End", "", "", "", "", "", "");
-}
-
-// static
-bool TraceEventETWExport::IsCategoryGroupEnabled(
-    StringPiece category_group_name) {
-  DCHECK(!category_group_name.empty());
-  auto* instance = GetInstance();
-  if (instance == nullptr)
-    return false;
-
-  if (!instance->IsETWExportEnabled())
-    return false;
-
-  CStringTokenizer category_group_tokens(category_group_name.begin(),
-                                         category_group_name.end(), ",");
-  while (category_group_tokens.GetNext()) {
-    StringPiece category_group_token = category_group_tokens.token_piece();
-    if (instance->IsCategoryEnabled(category_group_token)) {
-      return true;
-    }
-  }
-  return false;
-}
-
-bool TraceEventETWExport::UpdateEnabledCategories() {
-  if (etw_match_any_keyword_ == CHROME_Context.MatchAnyKeyword)
-    return false;
-
-  // If the keyword has changed, update each category.
-  // Chrome_Context.MatchAnyKeyword is set by UIforETW (or other ETW trace
-  // recording tools) using the ETW infrastructure. This value will be set in
-  // all Chrome processes that have registered their ETW provider.
-  etw_match_any_keyword_ = CHROME_Context.MatchAnyKeyword;
-  for (size_t i = 0; i < ARRAYSIZE(kFilteredEventGroupNames); i++) {
-    if (etw_match_any_keyword_ & (1ULL << i)) {
-      categories_status_[kFilteredEventGroupNames[i]] = true;
-    } else {
-      categories_status_[kFilteredEventGroupNames[i]] = false;
-    }
-  }
-
-  // Also update the two default categories.
-  if (etw_match_any_keyword_ & kOtherEventsKeywordBit) {
-    categories_status_[kOtherEventsGroupName] = true;
-  } else {
-    categories_status_[kOtherEventsGroupName] = false;
-  }
-  if (etw_match_any_keyword_ & kDisabledOtherEventsKeywordBit) {
-    categories_status_[kDisabledOtherEventsGroupName] = true;
-  } else {
-    categories_status_[kDisabledOtherEventsGroupName] = false;
-  }
-
-  DCHECK_EQ(kNumberOfCategories, categories_status_.size());
-
-  // Update the categories in TraceLog.
-  TraceLog::GetInstance()->UpdateETWCategoryGroupEnabledFlags();
-
-  return true;
-}
-
-bool TraceEventETWExport::IsCategoryEnabled(StringPiece category_name) const {
-  DCHECK_EQ(kNumberOfCategories, categories_status_.size());
-  // Try to find the category and return its status if found
-  auto it = categories_status_.find(category_name);
-  if (it != categories_status_.end())
-    return it->second;
-
-  // Otherwise return the corresponding default status by first checking if the
-  // category is disabled by default.
-  if (category_name.starts_with("disabled-by-default")) {
-    DCHECK(categories_status_.find(kDisabledOtherEventsGroupName) !=
-           categories_status_.end());
-    return categories_status_.find(kDisabledOtherEventsGroupName)->second;
-  } else {
-    DCHECK(categories_status_.find(kOtherEventsGroupName) !=
-           categories_status_.end());
-    return categories_status_.find(kOtherEventsGroupName)->second;
-  }
-}
-
-// static
-void TraceEventETWExport::UpdateETWKeyword() {
-  if (!IsETWExportEnabled())
-    return;
-  auto* instance = GetInstance();
-  DCHECK(instance);
-  instance->UpdateEnabledCategories();
-}
-}  // namespace trace_event
-}  // namespace base
diff --git a/base/trace_event/trace_event_etw_export_win.h b/base/trace_event/trace_event_etw_export_win.h
deleted file mode 100644
index 8a85b22..0000000
--- a/base/trace_event/trace_event_etw_export_win.h
+++ /dev/null
@@ -1,99 +0,0 @@
-// Copyright 2015 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 file contains the Windows-specific exporting to ETW.
-#ifndef BASE_TRACE_EVENT_TRACE_EVENT_ETW_EXPORT_WIN_H_
-#define BASE_TRACE_EVENT_TRACE_EVENT_ETW_EXPORT_WIN_H_
-
-#include <stdint.h>
-
-#include <map>
-
-#include "base/base_export.h"
-#include "base/macros.h"
-#include "base/strings/string_piece.h"
-#include "base/trace_event/trace_event_impl.h"
-
-namespace base {
-
-template <typename Type>
-struct StaticMemorySingletonTraits;
-
-namespace trace_event {
-
-class BASE_EXPORT TraceEventETWExport {
- public:
-  ~TraceEventETWExport();
-
-  // Retrieves the singleton.
-  // Note that this may return NULL post-AtExit processing.
-  static TraceEventETWExport* GetInstance();
-
-  // Enables/disables exporting of events to ETW. If disabled,
-  // AddEvent and AddCustomEvent will simply return when called.
-  static void EnableETWExport();
-  static void DisableETWExport();
-
-  // Returns true if ETW is enabled. For now, this is true if the command line
-  // flag is specified.
-  static bool IsETWExportEnabled();
-
-  // Exports an event to ETW. This is mainly used in
-  // TraceLog::AddTraceEventWithThreadIdAndTimestamp to export internal events.
-  static void AddEvent(
-      char phase,
-      const unsigned char* category_group_enabled,
-      const char* name,
-      unsigned long long id,
-      int num_args,
-      const char* const* arg_names,
-      const unsigned char* arg_types,
-      const unsigned long long* arg_values,
-      const std::unique_ptr<ConvertableToTraceFormat>* convertable_values);
-
-  // Exports an ETW event that marks the end of a complete event.
-  static void AddCompleteEndEvent(const char* name);
-
-  // Returns true if any category in the group is enabled.
-  static bool IsCategoryGroupEnabled(StringPiece category_group_name);
-
- private:
-  // Ensure only the provider can construct us.
-  friend struct StaticMemorySingletonTraits<TraceEventETWExport>;
-  // To have access to UpdateKeyword().
-  class ETWKeywordUpdateThread;
-  TraceEventETWExport();
-
-  // Updates the list of enabled categories by consulting the ETW keyword.
-  // Returns true if there was a change, false otherwise.
-  bool UpdateEnabledCategories();
-
-  // Returns true if the category is enabled.
-  bool IsCategoryEnabled(StringPiece category_name) const;
-
-  // Called back by the update thread to check for potential changes to the
-  // keyword.
-  static void UpdateETWKeyword();
-
-  // True if ETW is enabled. Allows hiding the exporting behind a flag.
-  bool etw_export_enabled_;
-
-  // Maps category names to their status (enabled/disabled).
-  std::map<StringPiece, bool> categories_status_;
-
-  // Local copy of the ETW keyword.
-  uint64_t etw_match_any_keyword_;
-
-  // Background thread that monitors changes to the ETW keyword and updates
-  // the enabled categories when a change occurs.
-  std::unique_ptr<ETWKeywordUpdateThread> keyword_update_thread_;
-  PlatformThreadHandle keyword_update_thread_handle_;
-
-  DISALLOW_COPY_AND_ASSIGN(TraceEventETWExport);
-};
-
-}  // namespace trace_event
-}  // namespace base
-
-#endif  // BASE_TRACE_EVENT_TRACE_EVENT_ETW_EXPORT_WIN_H_
diff --git a/base/trace_event/trace_log.cc b/base/trace_event/trace_log.cc
index 0012c09..f608261 100644
--- a/base/trace_event/trace_log.cc
+++ b/base/trace_event/trace_log.cc
@@ -45,10 +45,6 @@
 #include "base/trace_event/trace_event.h"
 #include "build_config.h"
 
-#if defined(OS_WIN)
-#include "base/trace_event/trace_event_etw_export_win.h"
-#endif
-
 #if defined(OS_ANDROID)
 // The linker assigns the virtual address of the start of current library to
 // this symbol.
@@ -483,13 +479,6 @@
     state_flags |= TraceCategory::ENABLED_FOR_RECORDING;
   }
 
-#if defined(OS_WIN)
-  if (base::trace_event::TraceEventETWExport::IsCategoryGroupEnabled(
-          category->name())) {
-    state_flags |= TraceCategory::ENABLED_FOR_ETW_EXPORT;
-  }
-#endif
-
   uint32_t enabled_filters_bitmap = 0;
   int index = 0;
   for (const auto& event_filter : enabled_event_filters_) {
@@ -1243,15 +1232,6 @@
     }
   }
 
-#if defined(OS_WIN)
-  // This is done sooner rather than later, to avoid creating the event and
-  // acquiring the lock, which is not needed for ETW as it's already threadsafe.
-  if (*category_group_enabled & TraceCategory::ENABLED_FOR_ETW_EXPORT)
-    TraceEventETWExport::AddEvent(phase, category_group_enabled, name, id,
-                                  num_args, arg_names, arg_types, arg_values,
-                                  convertable_values);
-#endif  // OS_WIN
-
   AddTraceEventOverrideCallback trace_event_override =
       reinterpret_cast<AddTraceEventOverrideCallback>(
           subtle::NoBarrier_Load(&trace_event_override_));
@@ -1452,12 +1432,6 @@
     return;
   AutoThreadLocalBoolean thread_is_in_trace_event(&thread_is_in_trace_event_);
 
-#if defined(OS_WIN)
-  // Generate an ETW event that marks the end of a complete event.
-  if (category_group_enabled_local & TraceCategory::ENABLED_FOR_ETW_EXPORT)
-    TraceEventETWExport::AddCompleteEndEvent(name);
-#endif  // OS_WIN
-
   std::string console_message;
   if (category_group_enabled_local & TraceCategory::ENABLED_FOR_RECORDING) {
     AddTraceEventOverrideCallback trace_event_override =
@@ -1702,21 +1676,6 @@
       kTraceEventVectorBufferChunks);
 }
 
-#if defined(OS_WIN)
-void TraceLog::UpdateETWCategoryGroupEnabledFlags() {
-  // Go through each category and set/clear the ETW bit depending on whether the
-  // category is enabled.
-  for (TraceCategory& category : CategoryRegistry::GetAllCategories()) {
-    if (base::trace_event::TraceEventETWExport::IsCategoryGroupEnabled(
-            category.name())) {
-      category.set_state_flag(TraceCategory::ENABLED_FOR_ETW_EXPORT);
-    } else {
-      category.clear_state_flag(TraceCategory::ENABLED_FOR_ETW_EXPORT);
-    }
-  }
-}
-#endif  // defined(OS_WIN)
-
 void TraceLog::SetTraceBufferForTesting(
     std::unique_ptr<TraceBuffer> trace_buffer) {
   AutoLock lock(lock_);
diff --git a/base/trace_event/trace_log.h b/base/trace_event/trace_log.h
index 56df18d..e480323 100644
--- a/base/trace_event/trace_log.h
+++ b/base/trace_event/trace_log.h
@@ -343,13 +343,6 @@
   // may not handle the flush request in time causing lost of unflushed events.
   void SetCurrentThreadBlocksMessageLoop();
 
-#if defined(OS_WIN)
-  // This function is called by the ETW exporting module whenever the ETW
-  // keyword (flags) changes. This keyword indicates which categories should be
-  // exported, so whenever it changes, we adjust accordingly.
-  void UpdateETWCategoryGroupEnabledFlags();
-#endif
-
   // Replaces |logged_events_| with a new TraceBuffer for testing.
   void SetTraceBufferForTesting(std::unique_ptr<TraceBuffer> trace_buffer);
 
diff --git a/base/win/scoped_handle_verifier.cc b/base/win/scoped_handle_verifier.cc
index 6a73677..930d147 100644
--- a/base/win/scoped_handle_verifier.cc
+++ b/base/win/scoped_handle_verifier.cc
@@ -12,7 +12,6 @@
 #include "base/debug/alias.h"
 #include "base/debug/stack_trace.h"
 #include "base/synchronization/lock_impl.h"
-#include "base/win/base_win_buildflags.h"
 #include "base/win/current_module.h"
 
 extern "C" {
diff --git a/base/win/scoped_winrt_initializer.cc b/base/win/scoped_winrt_initializer.cc
deleted file mode 100644
index e05679a..0000000
--- a/base/win/scoped_winrt_initializer.cc
+++ /dev/null
@@ -1,38 +0,0 @@
-// 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.
-
-#include "base/win/scoped_winrt_initializer.h"
-
-#include "base/logging.h"
-#include "base/win/com_init_util.h"
-#include "base/win/core_winrt_util.h"
-#include "base/win/windows_version.h"
-
-namespace base {
-namespace win {
-
-ScopedWinrtInitializer::ScopedWinrtInitializer()
-    : hr_(base::win::RoInitialize(RO_INIT_MULTITHREADED)) {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
-  DCHECK_GE(GetVersion(), VERSION_WIN8);
-#if DCHECK_IS_ON()
-  if (SUCCEEDED(hr_))
-    AssertComApartmentType(ComApartmentType::MTA);
-  else
-    DCHECK_NE(RPC_E_CHANGED_MODE, hr_) << "Invalid COM thread model change";
-#endif
-}
-
-ScopedWinrtInitializer::~ScopedWinrtInitializer() {
-  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
-  if (SUCCEEDED(hr_))
-    base::win::RoUninitialize();
-}
-
-bool ScopedWinrtInitializer::Succeeded() const {
-  return SUCCEEDED(hr_);
-}
-
-}  // namespace win
-}  // namespace base
diff --git a/base/win/scoped_winrt_initializer.h b/base/win/scoped_winrt_initializer.h
deleted file mode 100644
index 7c76515..0000000
--- a/base/win/scoped_winrt_initializer.h
+++ /dev/null
@@ -1,48 +0,0 @@
-// 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_WIN_SCOPED_WINRT_INITIALIZER_H_
-#define BASE_WIN_SCOPED_WINRT_INITIALIZER_H_
-
-#include <objbase.h>
-
-#include "base/base_export.h"
-#include "base/threading/thread_checker.h"
-#include "base/win/scoped_windows_thread_environment.h"
-
-namespace base {
-namespace win {
-
-// Initializes the Windows Runtime in the constructor and uninitalizes the
-// Windows Runtime in the destructor. As a side effect, COM is also initialized
-// as an MTA in the constructor and correspondingly uninitialized in the
-// destructor.
-//
-// Generally, you should only use this on Windows 8 or above. It is redundant
-// to use ScopedComInitializer in conjunction with ScopedWinrtInitializer.
-//
-// WARNING: This should only be used once per thread, ideally scoped to a
-// similar lifetime as the thread itself. You should not be using this in random
-// utility functions that make Windows Runtime calls -- instead ensure these
-// functions are running on a Windows Runtime supporting thread!
-class BASE_EXPORT ScopedWinrtInitializer
-    : public ScopedWindowsThreadEnvironment {
- public:
-  ScopedWinrtInitializer();
-  ~ScopedWinrtInitializer() override;
-
-  // ScopedWindowsThreadEnvironment:
-  bool Succeeded() const override;
-
- private:
-  const HRESULT hr_;
-  THREAD_CHECKER(thread_checker_);
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedWinrtInitializer);
-};
-
-}  // namespace win
-}  // namespace base
-
-#endif  // BASE_WIN_SCOPED_WINRT_INITIALIZER_H_
diff --git a/build/build_win.ninja.template b/build/build_win.ninja.template
index f5f8b65..3edfb6a 100644
--- a/build/build_win.ninja.template
+++ b/build/build_win.ninja.template
@@ -1,27 +1,25 @@
-arch = environment.x64
-
 rule cc
-  command = ninja -t msvc -e $arch -- $cc /nologo /showIncludes /FC @${out}.rsp /c ${in} /Fo${out}
+  command = ninja -t msvc -- $cc /nologo /showIncludes /FC @${out}.rsp /c ${in} /Fo${out}
   description = CC ${out}
   rspfile = ${out}.rsp
   rspfile_content = ${defines} ${includes} ${cflags} ${cflags_c}
   deps = msvc
 
 rule cxx
-  command = ninja -t msvc -e $arch -- $cxx /nologo /showIncludes /FC @${out}.rsp /c ${in} /Fo${out}
+  command = ninja -t msvc -- $cxx /nologo /showIncludes /FC @${out}.rsp /c ${in} /Fo${out}
   description = CXX ${out}
   rspfile = ${out}.rsp
   rspfile_content = ${defines} ${includes} ${cflags} ${cflags_cc}
   deps = msvc
 
 rule alink_thin
-  command = ninja -t msvc -e $arch -- $ar /nologo /ignore:4221 /OUT:${out} @${out}.rsp
+  command = ninja -t msvc -- $ar /nologo /ignore:4221 /OUT:${out} @${out}.rsp
   description = LIB ${out}
   rspfile = ${out}.rsp
-  rspfile_content = ${in_newline}
+  rspfile_content = ${in_newline} ${libflags}
 
 rule link
-  command = ninja -t msvc -e $arch -- $ld /nologo /OUT:${out} /PDB:${out}.pdb @${out}.rsp
+  command = ninja -t msvc -- $ld /nologo /OUT:${out} /PDB:${out}.pdb @${out}.rsp
   description = LINK ${out}
   rspfile = ${out}.rsp
   rspfile_content = ${in_newline} ${libs} ${solibs} ${ldflags}
diff --git a/build/gen.py b/build/gen.py
index 6d551eb..6c73d4e 100755
--- a/build/gen.py
+++ b/build/gen.py
@@ -47,8 +47,8 @@
 
 
 def write_generic_ninja(path, static_libraries, executables,
-                        cc, cxx, ar, ld,
-                        cflags=[], cflags_cc=[], ldflags=[],
+                        cc, cxx, ar, ld, options,
+                        cflags=[], cflags_cc=[], ldflags=[], libflags=[],
                         include_dirs=[], solibs=[]):
   ninja_header_lines = [
     'cc = ' + cc,
@@ -57,7 +57,8 @@
     'ld = ' + ld,
     '',
     'rule regen',
-    '  command = %s ../build/gen.py' % sys.executable,
+    '  command = %s ../build/gen.py%s' % (
+        sys.executable, ' -d' if options.debug else ''),
     '  description = Regenerating ninja files',
     '',
     'build build.ninja: regen',
@@ -116,6 +117,8 @@
     ninja_lines.append('build %s: alink_thin %s' % (
         library_to_a(library),
         ' '.join([src_to_obj(src_file) for src_file in settings['sources']])))
+    ninja_lines.append('  libflags = %s' % ' '.join(libflags))
+
 
   for executable, settings in executables.iteritems():
     for src_file in settings['sources']:
@@ -161,6 +164,7 @@
   cflags = os.environ.get('CFLAGS', '').split()
   cflags_cc = os.environ.get('CXXFLAGS', '').split()
   ldflags = os.environ.get('LDFLAGS', '').split()
+  libflags = os.environ.get('LIBFLAGS', '').split()
   include_dirs = [REPO_ROOT, os.path.join(REPO_ROOT, 'src')]
   libs = []
 
@@ -191,24 +195,37 @@
   elif is_win:
     if not options.debug:
       cflags.extend(['/Ox', '/DNDEBUG', '/GL'])
+      libflags.extend(['/LTCG'])
       ldflags.extend(['/LTCG', '/OPT:REF', '/OPT:ICF'])
 
     cflags.extend([
+        '/DNOMINMAX',
+        '/DUNICODE',
+        '/DWIN32_LEAN_AND_MEAN',
+        '/DWINVER=0x0A00',
+        '/D_CRT_SECURE_NO_DEPRECATE',
+        '/D_SCL_SECURE_NO_DEPRECATE',
+        '/D_UNICODE',
+        '/D_WIN32_WINNT=0x0A00',
         '/FS',
         '/Gy',
-        '/W3', '/wd4244',
+        '/W4',
+        '/WX',
         '/Zi',
-        '/DWIN32_LEAN_AND_MEAN', '/DNOMINMAX',
-        '/D_CRT_SECURE_NO_DEPRECATE', '/D_SCL_SECURE_NO_DEPRECATE',
-        '/D_WIN32_WINNT=0x0A00', '/DWINVER=0x0A00',
-        '/DUNICODE', '/D_UNICODE',
+        '/wd4099',
+        '/wd4100',
+        '/wd4127',
+        '/wd4244',
+        '/wd4267',
+        '/wd4838',
+        '/wd4996',
     ])
     cflags_cc.extend([
         '/GR-',
         '/D_HAS_EXCEPTIONS=0',
     ])
 
-    ldflags.extend(['/MACHINE:x64'])
+    ldflags.extend(['/DEBUG', '/MACHINE:x64'])
 
   static_libraries = {
       'base': {'sources': [
@@ -789,7 +806,6 @@
         'base/threading/thread_local_storage_win.cc',
         'base/time/time_win.cc',
         'base/timer/hi_res_timer_manager_win.cc',
-        'base/trace_event/trace_event_etw_export_win.cc',
         'base/win/core_winrt_util.cc',
         'base/win/enum_variant.cc',
         'base/win/event_trace_controller.cc',
@@ -809,7 +825,6 @@
         'base/win/scoped_handle_verifier.cc',
         'base/win/scoped_process_information.cc',
         'base/win/scoped_variant.cc',
-        'base/win/scoped_winrt_initializer.cc',
         'base/win/shortcut.cc',
         'base/win/startup_information.cc',
         'base/win/wait_chain.cc',
@@ -837,7 +852,8 @@
   executables['gn_unittests']['libs'].extend(static_libraries.keys())
 
   write_generic_ninja(path, static_libraries, executables, cc, cxx, ar, ld,
-                      cflags, cflags_cc, ldflags, include_dirs, libs)
+                      options, cflags, cflags_cc, ldflags, libflags,
+                      include_dirs, libs)
 
 
 if __name__ == '__main__':
diff --git a/src/test/gn_test.cc b/src/test/gn_test.cc
index 4d16195..0763048 100644
--- a/src/test/gn_test.cc
+++ b/src/test/gn_test.cc
@@ -120,10 +120,13 @@
     }
   }
 
-  int nactivetests = 0;
-  for (int i = 0; i < ntests; i++)
-    if ((tests[i].should_run = TestMatchesFilter(tests[i].name, test_filter)))
-      ++nactivetests;
+  int num_active_tests = 0;
+  for (int i = 0; i < ntests; i++) {
+    tests[i].should_run = TestMatchesFilter(tests[i].name, test_filter);
+    if (tests[i].should_run) {
+      ++num_active_tests;
+    }
+  }
 
   const char* prefix = "";
   const char* suffix = "\n";
@@ -143,8 +146,8 @@
 
     ++tests_started;
     testing::Test* test = tests[i].factory();
-    printf("%s[%d/%d] %s%s", prefix, tests_started, nactivetests, tests[i].name,
-           suffix);
+    printf("%s[%d/%d] %s%s", prefix, tests_started, num_active_tests,
+           tests[i].name, suffix);
     test->SetUp();
     test->Run();
     test->TearDown();
diff --git a/tools/gn/input_conversion.cc b/tools/gn/input_conversion.cc
index a7abcf4..22d33ca 100644
--- a/tools/gn/input_conversion.cc
+++ b/tools/gn/input_conversion.cc
@@ -142,7 +142,7 @@
     case base::Value::Type::DICTIONARY: {
       std::unique_ptr<Scope> scope = std::make_unique<Scope>(settings);
       for (const auto& it : value.DictItems()) {
-        Value value =
+        Value parsed_value =
             ParseJSONValue(settings, it.second, origin, input_file, err);
         if (!IsIdentifier(it.first)) {
           *err = Err(origin, "Invalid identifier \"" + it.first + "\".");
@@ -158,7 +158,7 @@
         }
         base::StringPiece key(&input_file->contents()[off + 1],
                               it.first.size());
-        scope->SetValue(key, std::move(value), origin);
+        scope->SetValue(key, std::move(parsed_value), origin);
       }
       return Value(origin, std::move(scope));
     }
@@ -166,8 +166,9 @@
       Value result(origin, Value::LIST);
       result.list_value().reserve(value.GetList().size());
       for (const auto& val : value.GetList()) {
-        Value value = ParseJSONValue(settings, val, origin, input_file, err);
-        result.list_value().push_back(value);
+        Value parsed_value =
+            ParseJSONValue(settings, val, origin, input_file, err);
+        result.list_value().push_back(parsed_value);
       }
       return result;
     }