Move ThreadWrapper to ProcessThread in base.

webrtc/system_wrappers/source/event_timer_posix.h

 /*
  *  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_EVENT_POSIX_H_
 #define WEBRTC_SYSTEM_WRAPPERS_SOURCE_EVENT_POSIX_H_
 
 #include "webrtc/system_wrappers/include/event_wrapper.h"
 
 #include <pthread.h>
 #include <time.h>
 
-#include "webrtc/system_wrappers/include/thread_wrapper.h"
+#include "webrtc/base/platform_thread.h"
 
 namespace webrtc {
 
 enum State {
   kUp = 1,
   kDown = 2
 };
 
 class EventTimerPosix : public EventTimerWrapper {
  public:
   EventTimerPosix();
   ~EventTimerPosix() override;
 
   EventTypeWrapper Wait(unsigned long max_time) override;
   bool Set() override;
 
   bool StartTimer(bool periodic, unsigned long time) override;
   bool StopTimer() override;
 
  private:
   static bool Run(void* obj);
   bool Process();
   EventTypeWrapper Wait(timespec* end_at);
 
  private:
   pthread_cond_t  cond_;
   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_;
 
   bool          periodic_;
   unsigned long time_;  // In ms
   unsigned long count_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_SYSTEM_WRAPPERS_SOURCE_EVENT_POSIX_H_