Replace the stop_event_ in PlatformThread with an atomic flag

webrtc/base/platform_thread.h

 /*
  *  Copyright (c) 2015 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.
  */
 
@@ skipping 76 matching lines @@
 
   ThreadRunFunction const run_function_;
   void* const obj_;
   // TODO(pbos): Make sure call sites use string literals and update to a const
   // char* instead of a std::string.
   const std::string name_;
   rtc::ThreadChecker thread_checker_;
 #if defined(WEBRTC_WIN)
   static DWORD WINAPI StartThread(void* param);
 
-  bool stop_;
-  HANDLE thread_;
-  DWORD thread_id_;
+  bool stop_ = false;
+  HANDLE thread_ = nullptr;
+  DWORD thread_id_ = 0;
 #else
   static void* StartThread(void* param);
 
-  rtc::Event stop_event_;
-
-  pthread_t thread_;
+  // An atomic flag that we use to stop the thread. Only modified on the
+  // controlling thread and checked on the worker thread.
+  volatile int stop_flag_ = 0;
+  pthread_t thread_ = 0;
 #endif  // defined(WEBRTC_WIN)
   RTC_DISALLOW_COPY_AND_ASSIGN(PlatformThread);
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_PLATFORM_THREAD_H_