Allow ObserverListThreadSafe to be used from sequenced tasks.

media/cast/test/receiver.cc

 // Copyright 2013 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 <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <climits>
 #include <cstdarg>
 #include <cstdio>
 #include <deque>
 #include <map>
 #include <memory>
 #include <string>
 #include <utility>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "base/time/default_tick_clock.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/fake_audio_log_factory.h"
 #include "media/base/audio_bus.h"
 #include "media/base/audio_parameters.h"
 #include "media/base/channel_layout.h"
 #include "media/base/video_frame.h"
@@ skipping 567 matching lines @@
                                   audio_config,
                                   video_config,
                                   window_width,
                                   window_height);
   player.Start();
 
   base::RunLoop().Run();  // Run forever (i.e., until SIGTERM).
   NOTREACHED();
   return 0;
 }