Move ThreadWrapper to ProcessThread in base.

Also removes all virtual methods. Permits using a thread from
rtc_base_approved (namely event tracing).

BUG=webrtc:5158
R=tommi@webrtc.org

Review URL: https://codereview.webrtc.org/1469013002

Cr-Commit-Position: refs/heads/master@{#10760}

18 files changed, 16 insertions, 601 deletions

diff --git a/webrtc/system_wrappers/BUILD.gn b/webrtc/system_wrappers/BUILD.gn
index d0447e9ca1..5e0e41e832 100644
--- a/webrtc/system_wrappers/BUILD.gn
+++ b/webrtc/system_wrappers/BUILD.gn
@@ -37,7 +37,6 @@ static_library("system_wrappers") {
     "include/static_instance.h",
     "include/stl_util.h",
     "include/stringize_macros.h",
-    "include/thread_wrapper.h",
     "include/tick_util.h",
     "include/timestamp_extrapolator.h",
     "include/trace.h",
@@ -79,11 +78,6 @@ static_library("system_wrappers") {
     "source/rw_lock_win.h",
     "source/sleep.cc",
     "source/sort.cc",
-    "source/thread.cc",
-    "source/thread_posix.cc",
-    "source/thread_posix.h",
-    "source/thread_win.cc",
-    "source/thread_win.h",
     "source/tick_util.cc",
     "source/timestamp_extrapolator.cc",
     "source/trace_impl.cc",
@@ -193,9 +187,9 @@ source_set("system_wrappers_default") {
   public_configs = [ "..:common_inherited_config" ]
 
   deps = [
-    ":system_wrappers",
     ":field_trial_default",
     ":metrics_default",
+    ":system_wrappers",
   ]
 }
 
diff --git a/webrtc/system_wrappers/include/data_log_impl.h b/webrtc/system_wrappers/include/data_log_impl.h
index 1932a345b6..723cca31fb 100644
--- a/webrtc/system_wrappers/include/data_log_impl.h
+++ b/webrtc/system_wrappers/include/data_log_impl.h
@@ -22,8 +22,8 @@
 #include <string>
 #include <vector>
 
+#include "webrtc/base/platform_thread.h"
 #include "webrtc/base/scoped_ptr.h"
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
@@ -146,7 +146,7 @@ class DataLogImpl {
   int                       counter_;
   TableMap                  tables_;
   EventWrapper*             flush_event_;
-  rtc::scoped_ptr<ThreadWrapper> file_writer_thread_;
+  rtc::scoped_ptr<PlatformThread> file_writer_thread_;
   RWLockWrapper*            tables_lock_;
 };
 
diff --git a/webrtc/system_wrappers/include/thread_wrapper.h b/webrtc/system_wrappers/include/thread_wrapper.h
deleted file mode 100644
index dbd548dfd9..0000000000
--- a/webrtc/system_wrappers/include/thread_wrapper.h
+++ /dev/null
@@ -1,89 +0,0 @@
-/*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-// System independant wrapper for spawning threads
-// Note: the spawned thread will loop over the callback function until stopped.
-// Note: The callback function is expected to return every 2 seconds or more
-// often.
-
-#ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_THREAD_WRAPPER_H_
-#define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_THREAD_WRAPPER_H_
-
-#if defined(WEBRTC_WIN)
-#include <windows.h>
-#endif
-
-#include "webrtc/base/scoped_ptr.h"
-#include "webrtc/common_types.h"
-#include "webrtc/typedefs.h"
-
-namespace webrtc {
-
-// Callback function that the spawned thread will enter once spawned.
-// A return value of false is interpreted as that the function has no
-// more work to do and that the thread can be released.
-typedef bool(*ThreadRunFunction)(void*);
-
-enum ThreadPriority {
-#ifdef WEBRTC_WIN
-  kLowPriority = THREAD_PRIORITY_BELOW_NORMAL,
-  kNormalPriority = THREAD_PRIORITY_NORMAL,
-  kHighPriority = THREAD_PRIORITY_ABOVE_NORMAL,
-  kHighestPriority = THREAD_PRIORITY_HIGHEST,
-  kRealtimePriority = THREAD_PRIORITY_TIME_CRITICAL
-#else
-  kLowPriority = 1,
-  kNormalPriority = 2,
-  kHighPriority = 3,
-  kHighestPriority = 4,
-  kRealtimePriority = 5
-#endif
-};
-
-// Represents a simple worker thread.  The implementation must be assumed
-// to be single threaded, meaning that all methods of the class, must be
-// called from the same thread, including instantiation.
-// TODO(tommi): There's no need for this to be a virtual interface since there's
-// only ever a single implementation of it.
-class ThreadWrapper {
- public:
-  virtual ~ThreadWrapper() {}
-
-  // Factory method. Constructor disabled.
-  //
-  // func        Pointer to a, by user, specified callback function.
-  // obj         Object associated with the thread. Passed in the callback
-  //             function.
-  // prio        Thread priority. May require root/admin rights.
-  // thread_name  NULL terminated thread name, will be visable in the Windows
-  //             debugger.
-  static rtc::scoped_ptr<ThreadWrapper> CreateThread(ThreadRunFunction func,
-      void* obj, const char* thread_name);
-
-  // Tries to spawns a thread and returns true if that was successful.
-  // Additionally, it tries to set thread priority according to the priority
-  // from when CreateThread was called. However, failure to set priority will
-  // not result in a false return value.
-  virtual bool Start() = 0;
-
-  // Stops the spawned thread and waits for it to be reclaimed with a timeout
-  // of two seconds. Will return false if the thread was not reclaimed.
-  // Multiple tries to Stop are allowed (e.g. to wait longer than 2 seconds).
-  // It's ok to call Stop() even if the spawned thread has been reclaimed.
-  virtual bool Stop() = 0;
-
-  // Set the priority of the worker thread.  Must be called when thread
-  // is running.
-  virtual bool SetPriority(ThreadPriority priority) = 0;
-};
-
-}  // namespace webrtc
-
-#endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_THREAD_WRAPPER_H_
diff --git a/webrtc/system_wrappers/source/condition_variable_unittest.cc b/webrtc/system_wrappers/source/condition_variable_unittest.cc
index ed845cc21e..aad55ac611 100644
--- a/webrtc/system_wrappers/source/condition_variable_unittest.cc
+++ b/webrtc/system_wrappers/source/condition_variable_unittest.cc
@@ -11,9 +11,9 @@
 #include "webrtc/system_wrappers/include/condition_variable_wrapper.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/platform_thread.h"
 #include "webrtc/base/scoped_ptr.h"
 #include "webrtc/system_wrappers/include/critical_section_wrapper.h"
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
 #include "webrtc/system_wrappers/include/tick_util.h"
 #include "webrtc/system_wrappers/include/trace.h"
 
@@ -147,8 +147,8 @@ class CondVarTest : public ::testing::Test {
   CondVarTest() {}
 
   virtual void SetUp() {
-    thread_ = ThreadWrapper::CreateThread(&WaitingRunFunction,
-                                          &baton_, "CondVarTest");
+    thread_ = PlatformThread::CreateThread(&WaitingRunFunction, &baton_,
+                                           "CondVarTest");
     ASSERT_TRUE(thread_->Start());
   }
 
@@ -167,7 +167,7 @@ class CondVarTest : public ::testing::Test {
   Baton baton_;
 
  private:
-  rtc::scoped_ptr<ThreadWrapper> thread_;
+  rtc::scoped_ptr<PlatformThread> thread_;
 };
 
 // The SetUp and TearDown functions use condition variables.
diff --git a/webrtc/system_wrappers/source/critical_section_unittest.cc b/webrtc/system_wrappers/source/critical_section_unittest.cc
index 6848bdd06b..347cb55c91 100644
--- a/webrtc/system_wrappers/source/critical_section_unittest.cc
+++ b/webrtc/system_wrappers/source/critical_section_unittest.cc
@@ -12,7 +12,7 @@
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "webrtc/system_wrappers/include/sleep.h"
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
+#include "webrtc/base/platform_thread.h"
 #include "webrtc/system_wrappers/include/trace.h"
 
 namespace webrtc {
@@ -78,7 +78,7 @@ TEST_F(CritSectTest, ThreadWakesOnce) NO_THREAD_SAFETY_ANALYSIS {
   CriticalSectionWrapper* crit_sect =
       CriticalSectionWrapper::CreateCriticalSection();
   ProtectedCount count(crit_sect);
-  rtc::scoped_ptr<ThreadWrapper> thread = ThreadWrapper::CreateThread(
+  rtc::scoped_ptr<PlatformThread> thread = PlatformThread::CreateThread(
       &LockUnlockThenStopRunFunction, &count, "ThreadWakesOnce");
   crit_sect->Enter();
   ASSERT_TRUE(thread->Start());
@@ -105,7 +105,7 @@ TEST_F(CritSectTest, ThreadWakesTwice) NO_THREAD_SAFETY_ANALYSIS {
   CriticalSectionWrapper* crit_sect =
       CriticalSectionWrapper::CreateCriticalSection();
   ProtectedCount count(crit_sect);
-  rtc::scoped_ptr<ThreadWrapper> thread = ThreadWrapper::CreateThread(
+  rtc::scoped_ptr<PlatformThread> thread = PlatformThread::CreateThread(
       &LockUnlockRunFunction, &count, "ThreadWakesTwice");
   crit_sect->Enter();  // Make sure counter stays 0 until we wait for it.
   ASSERT_TRUE(thread->Start());
diff --git a/webrtc/system_wrappers/source/data_log.cc b/webrtc/system_wrappers/source/data_log.cc
index dbc8ea1505..c25971d98a 100644
--- a/webrtc/system_wrappers/source/data_log.cc
+++ b/webrtc/system_wrappers/source/data_log.cc
@@ -348,8 +348,8 @@ int DataLogImpl::CreateLog() {
 }
 
 int DataLogImpl::Init() {
-  file_writer_thread_ = ThreadWrapper::CreateThread(
-      DataLogImpl::Run, instance_, "DataLog");
+  file_writer_thread_ =
+      PlatformThread::CreateThread(DataLogImpl::Run, instance_, "DataLog");
   bool success = file_writer_thread_->Start();
   if (!success)
     return -1;
diff --git a/webrtc/system_wrappers/source/event_timer_posix.cc b/webrtc/system_wrappers/source/event_timer_posix.cc
index 99eebcb70a..ff26e76ec0 100644
--- a/webrtc/system_wrappers/source/event_timer_posix.cc
+++ b/webrtc/system_wrappers/source/event_timer_posix.cc
@@ -154,7 +154,7 @@ bool EventTimerPosix::StartTimer(bool periodic, unsigned long time) {
   // Start the timer thread
   timer_event_.reset(new EventTimerPosix());
   const char* thread_name = "WebRtc_event_timer_thread";
-  timer_thread_ = ThreadWrapper::CreateThread(Run, this, thread_name);
+  timer_thread_ = PlatformThread::CreateThread(Run, this, thread_name);
   periodic_ = periodic;
   time_ = time;
   bool started = timer_thread_->Start();
diff --git a/webrtc/system_wrappers/source/event_timer_posix.h b/webrtc/system_wrappers/source/event_timer_posix.h
index 21c4ac702e..6e45b387f9 100644
--- a/webrtc/system_wrappers/source/event_timer_posix.h
+++ b/webrtc/system_wrappers/source/event_timer_posix.h
@@ -16,7 +16,7 @@
 #include <pthread.h>
 #include <time.h>
 
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
+#include "webrtc/base/platform_thread.h"
 
 namespace webrtc {
 
@@ -46,7 +46,7 @@ class EventTimerPosix : public EventTimerWrapper {
   pthread_mutex_t mutex_;
   bool event_set_;
 
-  rtc::scoped_ptr<ThreadWrapper> timer_thread_;
+  rtc::scoped_ptr<PlatformThread> timer_thread_;
   rtc::scoped_ptr<EventTimerPosix> timer_event_;
   timespec       created_at_;
 
diff --git a/webrtc/system_wrappers/source/thread.cc b/webrtc/system_wrappers/source/thread.cc
deleted file mode 100644
index 7da1e3d591..0000000000
--- a/webrtc/system_wrappers/source/thread.cc
+++ /dev/null
@@ -1,33 +0,0 @@
-/*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
-
-#if defined(_WIN32)
-#include "webrtc/system_wrappers/source/thread_win.h"
-#else
-#include "webrtc/system_wrappers/source/thread_posix.h"
-#endif
-
-namespace webrtc {
-
-#if defined(_WIN32)
-typedef ThreadWindows ThreadType;
-#else
-typedef ThreadPosix ThreadType;
-#endif
-
-rtc::scoped_ptr<ThreadWrapper> ThreadWrapper::CreateThread(
-    ThreadRunFunction func, void* obj, const char* thread_name) {
-  return rtc::scoped_ptr<ThreadWrapper>(
-      new ThreadType(func, obj, thread_name)).Pass();
-}
-
-}  // namespace webrtc
diff --git a/webrtc/system_wrappers/source/thread_posix.cc b/webrtc/system_wrappers/source/thread_posix.cc
deleted file mode 100644
index 952a3cd0f9..0000000000
--- a/webrtc/system_wrappers/source/thread_posix.cc
+++ /dev/null
@@ -1,161 +0,0 @@
-/*
- *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/system_wrappers/source/thread_posix.h"
-
-#include <algorithm>
-
-#include <errno.h>
-#include <unistd.h>
-#ifdef WEBRTC_LINUX
-#include <linux/unistd.h>
-#include <sched.h>
-#include <sys/types.h>
-#endif
-
-#include "webrtc/base/checks.h"
-#include "webrtc/system_wrappers/include/critical_section_wrapper.h"
-#include "webrtc/system_wrappers/include/event_wrapper.h"
-#include "webrtc/system_wrappers/include/sleep.h"
-#include "webrtc/system_wrappers/include/trace.h"
-
-namespace webrtc {
-namespace {
-struct ThreadAttributes {
-  ThreadAttributes() { pthread_attr_init(&attr); }
-  ~ThreadAttributes() { pthread_attr_destroy(&attr); }
-  pthread_attr_t* operator&() { return &attr; }
-  pthread_attr_t attr;
-};
-}  // namespace
-
-int ConvertToSystemPriority(ThreadPriority priority, int min_prio,
-                            int max_prio) {
-  RTC_DCHECK(max_prio - min_prio > 2);
-  const int top_prio = max_prio - 1;
-  const int low_prio = min_prio + 1;
-
-  switch (priority) {
-    case kLowPriority:
-      return low_prio;
-    case kNormalPriority:
-      // The -1 ensures that the kHighPriority is always greater or equal to
-      // kNormalPriority.
-      return (low_prio + top_prio - 1) / 2;
-    case kHighPriority:
-      return std::max(top_prio - 2, low_prio);
-    case kHighestPriority:
-      return std::max(top_prio - 1, low_prio);
-    case kRealtimePriority:
-      return top_prio;
-  }
-  RTC_DCHECK(false);
-  return low_prio;
-}
-
-// static
-void* ThreadPosix::StartThread(void* param) {
-  static_cast<ThreadPosix*>(param)->Run();
-  return 0;
-}
-
-ThreadPosix::ThreadPosix(ThreadRunFunction func, void* obj,
-                         const char* thread_name)
-    : run_function_(func),
-      obj_(obj),
-      stop_event_(false, false),
-      name_(thread_name ? thread_name : "webrtc"),
-      thread_(0) {
-  RTC_DCHECK(name_.length() < 64);
-}
-
-ThreadPosix::~ThreadPosix() {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
-}
-
-// TODO(pbos): Make Start void, calling code really doesn't support failures
-// here.
-bool ThreadPosix::Start() {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
-  RTC_DCHECK(!thread_) << "Thread already started?";
-
-  ThreadAttributes attr;
-  // Set the stack stack size to 1M.
-  pthread_attr_setstacksize(&attr, 1024 * 1024);
-  RTC_CHECK_EQ(0, pthread_create(&thread_, &attr, &StartThread, this));
-  return true;
-}
-
-bool ThreadPosix::Stop() {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
-  if (!thread_)
-    return true;
-
-  stop_event_.Set();
-  RTC_CHECK_EQ(0, pthread_join(thread_, nullptr));
-  thread_ = 0;
-
-  return true;
-}
-
-bool ThreadPosix::SetPriority(ThreadPriority priority) {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
-  if (!thread_)
-    return false;
-#if defined(WEBRTC_CHROMIUM_BUILD) && defined(WEBRTC_LINUX)
-  // TODO(tommi): Switch to the same mechanism as Chromium uses for
-  // changing thread priorities.
-  return true;
-#else
-#ifdef WEBRTC_THREAD_RR
-  const int policy = SCHED_RR;
-#else
-  const int policy = SCHED_FIFO;
-#endif
-  const int min_prio = sched_get_priority_min(policy);
-  const int max_prio = sched_get_priority_max(policy);
-  if (min_prio == -1 || max_prio == -1) {
-    WEBRTC_TRACE(kTraceError, kTraceUtility, -1,
-                 "unable to retreive min or max priority for threads");
-    return false;
-  }
-
-  if (max_prio - min_prio <= 2)
-    return false;
-
-  sched_param param;
-  param.sched_priority = ConvertToSystemPriority(priority, min_prio, max_prio);
-  if (pthread_setschedparam(thread_, policy, &param) != 0) {
-    WEBRTC_TRACE(
-        kTraceError, kTraceUtility, -1, "unable to set thread priority");
-    return false;
-  }
-
-  return true;
-#endif  // defined(WEBRTC_CHROMIUM_BUILD) && defined(WEBRTC_LINUX)
-}
-
-void ThreadPosix::Run() {
-  if (!name_.empty()) {
-    // Setting the thread name may fail (harmlessly) if running inside a
-    // sandbox. Ignore failures if they happen.
-    rtc::SetCurrentThreadName(name_.substr(0, 63).c_str());
-  }
-
-  // It's a requirement that for successful thread creation that the run
-  // function be called at least once (see RunFunctionIsCalled unit test),
-  // so to fullfill that requirement, we use a |do| loop and not |while|.
-  do {
-    if (!run_function_(obj_))
-      break;
-  } while (!stop_event_.Wait(0));
-}
-
-}  // namespace webrtc
diff --git a/webrtc/system_wrappers/source/thread_posix.h b/webrtc/system_wrappers/source/thread_posix.h
deleted file mode 100644
index bcdd732f86..0000000000
--- a/webrtc/system_wrappers/source/thread_posix.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_SYSTEM_WRAPPERS_SOURCE_THREAD_POSIX_H_
-#define WEBRTC_SYSTEM_WRAPPERS_SOURCE_THREAD_POSIX_H_
-
-#include "webrtc/base/event.h"
-#include "webrtc/base/scoped_ptr.h"
-#include "webrtc/base/thread_checker.h"
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
-
-#include <pthread.h>
-
-namespace webrtc {
-
-int ConvertToSystemPriority(ThreadPriority priority, int min_prio,
-                            int max_prio);
-
-class ThreadPosix : public ThreadWrapper {
- public:
-  ThreadPosix(ThreadRunFunction func, void* obj, const char* thread_name);
-  ~ThreadPosix() override;
-
-  // From ThreadWrapper.
-  bool Start() override;
-  bool Stop() override;
-
-  bool SetPriority(ThreadPriority priority) override;
-
- private:
-  static void* StartThread(void* param);
-
-  void Run();
-
-  rtc::ThreadChecker thread_checker_;
-  ThreadRunFunction const run_function_;
-  void* const obj_;
-  rtc::Event stop_event_;
-  const std::string name_;
-
-  pthread_t thread_;
-};
-
-}  // namespace webrtc
-
-#endif  // WEBRTC_SYSTEM_WRAPPERS_SOURCE_THREAD_POSIX_H_
diff --git a/webrtc/system_wrappers/source/thread_posix_unittest.cc b/webrtc/system_wrappers/source/thread_posix_unittest.cc
deleted file mode 100644
index edfb14502e..0000000000
--- a/webrtc/system_wrappers/source/thread_posix_unittest.cc
+++ /dev/null
@@ -1,30 +0,0 @@
-/*
- *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/system_wrappers/source/thread_posix.h"
-
-#include "testing/gtest/include/gtest/gtest.h"
-
-TEST(ThreadTestPosix, PrioritySettings) {
-  // API assumes that max_prio - min_prio > 2. Test the extreme case.
-  const int kMinPrio = -1;
-  const int kMaxPrio = 2;
-
-  int last_priority = kMinPrio;
-  for (int priority = webrtc::kLowPriority;
-       priority <= webrtc::kRealtimePriority; ++priority) {
-    int system_priority = webrtc::ConvertToSystemPriority(
-        static_cast<webrtc::ThreadPriority>(priority), kMinPrio, kMaxPrio);
-    EXPECT_GT(system_priority, kMinPrio);
-    EXPECT_LT(system_priority, kMaxPrio);
-    EXPECT_GE(system_priority, last_priority);
-    last_priority = system_priority;
-  }
-}
diff --git a/webrtc/system_wrappers/source/thread_unittest.cc b/webrtc/system_wrappers/source/thread_unittest.cc
deleted file mode 100644
index c8e180ba32..0000000000
--- a/webrtc/system_wrappers/source/thread_unittest.cc
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
-
-#include "testing/gtest/include/gtest/gtest.h"
-#include "webrtc/base/scoped_ptr.h"
-#include "webrtc/system_wrappers/include/sleep.h"
-
-namespace webrtc {
-
-// Function that does nothing, and reports success.
-bool NullRunFunction(void* obj) {
-  SleepMs(0);  // Hand over timeslice, prevents busy looping.
-  return true;
-}
-
-TEST(ThreadTest, StartStop) {
-  rtc::scoped_ptr<ThreadWrapper> thread = ThreadWrapper::CreateThread(
-      &NullRunFunction, nullptr, "ThreadTest");
-  ASSERT_TRUE(thread->Start());
-  EXPECT_TRUE(thread->Stop());
-}
-
-// Function that sets a boolean.
-bool SetFlagRunFunction(void* obj) {
-  bool* obj_as_bool = static_cast<bool*>(obj);
-  *obj_as_bool = true;
-  SleepMs(0);  // Hand over timeslice, prevents busy looping.
-  return true;
-}
-
-TEST(ThreadTest, RunFunctionIsCalled) {
-  bool flag = false;
-  rtc::scoped_ptr<ThreadWrapper> thread = ThreadWrapper::CreateThread(
-      &SetFlagRunFunction, &flag, "RunFunctionIsCalled");
-  ASSERT_TRUE(thread->Start());
-
-  // At this point, the flag may be either true or false.
-  EXPECT_TRUE(thread->Stop());
-
-  // We expect the thread to have run at least once.
-  EXPECT_TRUE(flag);
-}
-
-}  // namespace webrtc
diff --git a/webrtc/system_wrappers/source/thread_win.cc b/webrtc/system_wrappers/source/thread_win.cc
deleted file mode 100644
index b1c513c250..0000000000
--- a/webrtc/system_wrappers/source/thread_win.cc
+++ /dev/null
@@ -1,101 +0,0 @@
-/*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/system_wrappers/source/thread_win.h"
-
-#include <process.h>
-#include <stdio.h>
-#include <windows.h>
-
-#include "webrtc/base/checks.h"
-#include "webrtc/system_wrappers/include/trace.h"
-
-namespace webrtc {
-namespace {
-void CALLBACK RaiseFlag(ULONG_PTR param) {
-  *reinterpret_cast<bool*>(param) = true;
-}
-}
-
-ThreadWindows::ThreadWindows(ThreadRunFunction func, void* obj,
-                             const char* thread_name)
-    : run_function_(func),
-      obj_(obj),
-      stop_(false),
-      thread_(NULL),
-      name_(thread_name ? thread_name : "webrtc") {
-  RTC_DCHECK(func);
-}
-
-ThreadWindows::~ThreadWindows() {
-  RTC_DCHECK(main_thread_.CalledOnValidThread());
-  RTC_DCHECK(!thread_);
-}
-
-// static
-DWORD WINAPI ThreadWindows::StartThread(void* param) {
-  static_cast<ThreadWindows*>(param)->Run();
-  return 0;
-}
-
-bool ThreadWindows::Start() {
-  RTC_DCHECK(main_thread_.CalledOnValidThread());
-  RTC_DCHECK(!thread_);
-
-  stop_ = false;
-
-  // See bug 2902 for background on STACK_SIZE_PARAM_IS_A_RESERVATION.
-  // Set the reserved stack stack size to 1M, which is the default on Windows
-  // and Linux.
-  DWORD thread_id;
-  thread_ = ::CreateThread(NULL, 1024 * 1024, &StartThread, this,
-      STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id);
-  if (!thread_ ) {
-    RTC_DCHECK(false) << "CreateThread failed";
-    return false;
-  }
-
-  return true;
-}
-
-bool ThreadWindows::Stop() {
-  RTC_DCHECK(main_thread_.CalledOnValidThread());
-  if (thread_) {
-    // Set stop_ to |true| on the worker thread.
-    QueueUserAPC(&RaiseFlag, thread_, reinterpret_cast<ULONG_PTR>(&stop_));
-    WaitForSingleObject(thread_, INFINITE);
-    CloseHandle(thread_);
-    thread_ = nullptr;
-  }
-
-  return true;
-}
-
-bool ThreadWindows::SetPriority(ThreadPriority priority) {
-  RTC_DCHECK(main_thread_.CalledOnValidThread());
-  return thread_ && SetThreadPriority(thread_, priority);
-}
-
-void ThreadWindows::Run() {
-  if (!name_.empty())
-    rtc::SetCurrentThreadName(name_.c_str());
-
-  do {
-    // The interface contract of Start/Stop is that for a successfull call to
-    // Start, there should be at least one call to the run function.  So we
-    // call the function before checking |stop_|.
-    if (!run_function_(obj_))
-      break;
-    // Alertable sleep to permit RaiseFlag to run and update |stop_|.
-    SleepEx(0, true);
-  } while (!stop_);
-}
-
-}  // namespace webrtc
diff --git a/webrtc/system_wrappers/source/thread_win.h b/webrtc/system_wrappers/source/thread_win.h
deleted file mode 100644
index 34edd6d6c0..0000000000
--- a/webrtc/system_wrappers/source/thread_win.h
+++ /dev/null
@@ -1,48 +0,0 @@
-/*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_SYSTEM_WRAPPERS_SOURCE_THREAD_WIN_H_
-#define WEBRTC_SYSTEM_WRAPPERS_SOURCE_THREAD_WIN_H_
-
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
-
-#include <windows.h>
-
-#include "webrtc/base/thread_checker.h"
-
-namespace webrtc {
-
-class ThreadWindows : public ThreadWrapper {
- public:
-  ThreadWindows(ThreadRunFunction func, void* obj, const char* thread_name);
-  ~ThreadWindows() override;
-
-  bool Start() override;
-  bool Stop() override;
-
-  bool SetPriority(ThreadPriority priority) override;
-
- protected:
-  void Run();
-
- private:
-  static DWORD WINAPI StartThread(void* param);
-
-  ThreadRunFunction const run_function_;
-  void* const obj_;
-  bool stop_;
-  HANDLE thread_;
-  const std::string name_;
-  rtc::ThreadChecker main_thread_;
-};
-
-}  // namespace webrtc
-
-#endif  // WEBRTC_SYSTEM_WRAPPERS_SOURCE_THREAD_WIN_H_
diff --git a/webrtc/system_wrappers/source/trace_impl.h b/webrtc/system_wrappers/source/trace_impl.h
index ed49d9d0aa..c6d81d5b0b 100644
--- a/webrtc/system_wrappers/source/trace_impl.h
+++ b/webrtc/system_wrappers/source/trace_impl.h
@@ -16,7 +16,7 @@
 #include "webrtc/system_wrappers/include/event_wrapper.h"
 #include "webrtc/system_wrappers/include/file_wrapper.h"
 #include "webrtc/system_wrappers/include/static_instance.h"
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
+#include "webrtc/base/platform_thread.h"
 #include "webrtc/system_wrappers/include/trace.h"
 
 namespace webrtc {
diff --git a/webrtc/system_wrappers/system_wrappers.gyp b/webrtc/system_wrappers/system_wrappers.gyp
index 90ea79f80c..f5f2b2bdc8 100644
--- a/webrtc/system_wrappers/system_wrappers.gyp
+++ b/webrtc/system_wrappers/system_wrappers.gyp
@@ -44,7 +44,6 @@
         'include/static_instance.h',
         'include/stl_util.h',
         'include/stringize_macros.h',
-        'include/thread_wrapper.h',
         'include/tick_util.h',
         'include/timestamp_extrapolator.h',
         'include/trace.h',
@@ -91,11 +90,6 @@
         'source/sleep.cc',
         'source/sort.cc',
         'source/tick_util.cc',
-        'source/thread.cc',
-        'source/thread_posix.cc',
-        'source/thread_posix.h',
-        'source/thread_win.cc',
-        'source/thread_win.h',
         'source/timestamp_extrapolator.cc',
         'source/trace_impl.cc',
         'source/trace_impl.h',
diff --git a/webrtc/system_wrappers/system_wrappers_tests.gyp b/webrtc/system_wrappers/system_wrappers_tests.gyp
index 02bf627779..7f735337eb 100644
--- a/webrtc/system_wrappers/system_wrappers_tests.gyp
+++ b/webrtc/system_wrappers/system_wrappers_tests.gyp
@@ -33,8 +33,6 @@
         'source/scoped_vector_unittest.cc',
         'source/stringize_macros_unittest.cc',
         'source/stl_util_unittest.cc',
-        'source/thread_unittest.cc',
-        'source/thread_posix_unittest.cc',
       ],
       'conditions': [
         ['enable_data_logging==1', {
@@ -42,9 +40,6 @@
         }, {
           'sources!': [ 'source/data_log_unittest.cc', ],
         }],
-        ['os_posix==0', {
-          'sources!': [ 'source/thread_posix_unittest.cc', ],
-        }],
         ['OS=="android"', {
           'dependencies': [
             '<(DEPTH)/testing/android/native_test.gyp:native_test_native_code',