Monitor the IO message loop in the AudioDevice classes.

content/renderer/media/audio_device.h

 // Copyright (c) 2012 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.
 //
 // Audio rendering unit utilizing audio output stream provided by browser
 // process through IPC.
 //
 // Relationship of classes.
 //
 //  AudioOutputController                AudioDevice
@@ skipping 48 matching lines @@
 // - Pause() is asynchronous/non-blocking.
 // - The user must call Stop() before deleting the class instance.
 
 #ifndef CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_
 #define CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_
 #pragma once
 
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/message_loop.h"
 #include "base/shared_memory.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/simple_thread.h"
 #include "content/common/content_export.h"
 #include "content/renderer/media/audio_message_filter.h"
+#include "content/renderer/media/scoped_loop_observer.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_renderer_sink.h"
 
-namespace base {
-class WaitableEvent;
-}
-
 class CONTENT_EXPORT AudioDevice
     : NON_EXPORTED_BASE(public media::AudioRendererSink),
       public AudioMessageFilter::Delegate,
-      public base::DelegateSimpleThread::Delegate {
+      public base::DelegateSimpleThread::Delegate,
+      public ScopedLoopObserver {
  public:
   // Methods called on main render thread -------------------------------------
 
   // Minimal constructor where Initialize() must be called later.
   AudioDevice();
 
   AudioDevice(size_t buffer_size,
               int channels,
               double sample_rate,
               RenderCallback* callback);
@@ skipping 66 matching lines @@
   // continuous stream host just ignores it and assumes buffer is always filled
   // to its capacity.
   size_t FireRenderCallback(int16* data);
 
   // DelegateSimpleThread::Delegate implementation.
   virtual void Run() OVERRIDE;
 
   // Closes socket and joins with the audio thread.
   void ShutDownAudioThread();
 
+  // MessageLoop::DestructionObserver implementation for the IO loop.
+  // If the IO loop dies before we do, we shut down the audio thread from here.
+  virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
+
   // Format
   size_t buffer_size_;  // in sample-frames
   int channels_;
   int bits_per_sample_;
   double sample_rate_;
   AudioParameters::Format latency_format_;
 
   RenderCallback* callback_;
 
   // The client callback renders audio into here.
@@ skipping 35 matching lines @@
   // These variables must only be set on the IO thread while the audio_thread_
   // is not running.
   base::SharedMemoryHandle shared_memory_handle_;
   scoped_ptr<base::CancelableSyncSocket> audio_socket_;
   int memory_length_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDevice);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_