Mute audio when volume is zero on Android.

media/audio/audio_manager_base.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.
 
 #ifndef MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 
 #include <string>
 #include <utility>
 
@@ skipping 136 matching lines @@
       const AudioParameters& input_params) = 0;
 
   // Returns the ID of the default audio output device.
   // Implementations that don't yet support this should return an empty string.
   virtual std::string GetDefaultOutputDeviceID();
 
   // Get number of input or output streams.
   int input_stream_count() { return num_input_streams_; }
   int output_stream_count() { return num_output_streams_; }
 
+ protected:
+  // The message loop of the audio thread this object runs on. Used for internal
+  // tasks which run on the audio thread even after Shutdown() has been started
+  // and GetMessageLoop() starts returning NULL.
+  scoped_refptr<base::MessageLoopProxy> message_loop_;

[tommi (sloooow) - chröme, 2013/12/02 18:36:00]

I don't think we need this change so it would be great to revert (no other
platform needs it). Instead use GetMessageLoop.

[wjia(left Chromium), 2013/12/02 21:49:49]

Done.

+
  private:
   struct DispatcherParams;
   typedef ScopedVector<DispatcherParams> AudioOutputDispatchers;
 
   class CompareByParams;
 
   // Called by Shutdown().
   void ShutdownOnAudioThread();
 
   // Max number of open output streams, modified by
   // SetMaxOutputStreamsAllowed().
   int max_num_output_streams_;
 
   // Max number of open input streams.
   int max_num_input_streams_;
 
   // Number of currently open output streams.
   int num_output_streams_;
 
   // Number of currently open input streams.
   int num_input_streams_;
 
   // Track output state change listeners.
   ObserverList<AudioDeviceListener> output_listeners_;
 
   // Thread used to interact with audio streams created by this audio manager.
   base::Thread audio_thread_;
 
-  // The message loop of the audio thread this object runs on. Used for internal
-  // tasks which run on the audio thread even after Shutdown() has been started
-  // and GetMessageLoop() starts returning NULL.
-  scoped_refptr<base::MessageLoopProxy> message_loop_;
-
   // Map of cached AudioOutputDispatcher instances.  Must only be touched
   // from the audio thread (no locking).
   AudioOutputDispatchers output_dispatchers_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerBase);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_