Associate audio streams with their source/destination RenderView.

media/audio/audio_output_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                AudioOutputDevice
@@ skipping 81 matching lines @@
   // Methods called on IO thread ----------------------------------------------
   // AudioOutputIPCDelegate methods.
   virtual void OnStateChanged(AudioOutputIPCDelegate::State state) OVERRIDE;
   virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                                base::SyncSocket::Handle socket_handle,
                                int length) OVERRIDE;
   virtual void OnIPCClosed() OVERRIDE;
 
   // Creates an uninitialized AudioOutputDevice. Clients must call Initialize()
   // before using.
-  // TODO(tommi): When all dependencies on |content| have been removed
-  // from AudioOutputDevice, move this class over to media/audio.
   AudioOutputDevice(AudioOutputIPC* ipc,
                     const scoped_refptr<base::MessageLoopProxy>& io_loop);
 
+  // Returns the stream id used with the AudioOutputIPC interface.
+  int stream_id() const;
+
  protected:
   // Magic required by ref_counted.h to avoid any code deleting the object
   // accidentally while there are references to it.
   friend class base::RefCountedThreadSafe<AudioOutputDevice>;
   virtual ~AudioOutputDevice();
 
  private:
+  enum State {
+    kIpcClosed,  // No more IPCs can take place.

[scherkus (not reviewing), 2012/11/27 22:55:26]

chromium has decreed SHOUTING_STYLE for enum constants:
https://groups.google.com/a/chromium.org/d/topic/chromium-dev/RxEyIrolvs0/dis...

[miu, 2012/11/28 07:26:20]

Done.

+    kIdle,  // Not started.
+    kCreatingStream,  // Waiting for OnStreamCreated() to be called back.
+    kPaused,  // Paused.  OnStreamCreated() has been called.  Can Play()/Stop().
+    kPlaying,  // Playing back.  Can Pause()/Stop().
+  };
+
   // Methods called on IO thread ----------------------------------------------
   // The following methods are tasks posted on the IO thread that needs to
   // be executed on that thread. They interact with AudioMessageFilter and
   // sends IPC messages on that thread.
+  void RegisterDelegateOnIOThread(AudioOutputIPC* ipc);
   void CreateStreamOnIOThread(const AudioParameters& params,
                               int input_channels);
   void PlayOnIOThread();
   void PauseOnIOThread(bool flush);
   void ShutDownOnIOThread();
   void SetVolumeOnIOThread(double volume);
 
   // 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;
 
   AudioParameters audio_parameters_;
 
   // The number of optional synchronized input channels having the same
   // sample-rate and buffer-size as specified in audio_parameters_.
   int input_channels_;
 
   RenderCallback* callback_;
 
   // A pointer to the IPC layer that takes care of sending requests over to
   // the AudioRendererHost.
-  AudioOutputIPC* ipc_;
+  base::WeakPtr<AudioOutputIPC> ipc_;
 
   // Our stream ID on the message filter. Only accessed on the IO thread.
   // Must only be modified on the IO thread.
   int stream_id_;
 
+  // Current state (must only be accessed from the IO thread).  See comments for
+  // State enum above.
+  State state_;
+
   // State of Play() / Pause() calls before OnStreamCreated() is called.
   bool play_on_start_;
 
-  // Set to |true| when OnStreamCreated() is called.
-  // Set to |false| when ShutDownOnIOThread() is called.
-  // This is for use with play_on_start_ to track Play() / Pause() state.
-  // Must only be touched from the IO thread.
-  bool is_started_;
-
   // Our audio thread callback class.  See source file for details.
   class AudioThreadCallback;
 
   // In order to avoid a race between OnStreamCreated and Stop(), we use this
   // guard to control stopping and starting the audio thread.
   base::Lock audio_thread_lock_;
   AudioDeviceThread audio_thread_;
   scoped_ptr<AudioOutputDevice::AudioThreadCallback> audio_callback_;
 
   // Temporary hack to ignore OnStreamCreated() due to the user calling Stop()
   // so we don't start the audio thread pointing to a potentially freed
   // |callback_|.
   //
   // TODO(scherkus): Replace this by changing AudioRendererSink to either accept
   // the callback via Start(). See http://crbug.com/151051 for details.
   bool stopping_hack_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputDevice);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_DEVICE_H_