Caching AudioOutputDevice instances in mixer manager

media/base/audio_renderer_mixer.h

Index: media/base/audio_renderer_mixer.h
diff --git a/media/base/audio_renderer_mixer.h b/media/base/audio_renderer_mixer.h
index 7a6c1dd781bb96572e51dd71bbe96247d6ae6566..e37d4398e559a7bb122a47ebff4b5572ab78791e 100644
--- a/media/base/audio_renderer_mixer.h
+++ b/media/base/audio_renderer_mixer.h
@@ -26,8 +26,11 @@ namespace media {
 class MEDIA_EXPORT AudioRendererMixer
     : NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
  public:
+  typedef base::Callback<void(AudioRendererSink* sink)> ReleaseSinkCallback;
+
   AudioRendererMixer(const AudioParameters& output_params,
-                     const scoped_refptr<AudioRendererSink>& sink);
+                     AudioRendererSink* sink,
+                     const ReleaseSinkCallback& release_sink_cb);
   ~AudioRendererMixer() override;
 
   // Add or remove a mixer input from mixing; called by AudioRendererMixerInput.
@@ -64,7 +67,10 @@ class MEDIA_EXPORT AudioRendererMixer
   }
 
   // Output sink for this mixer.
-  scoped_refptr<AudioRendererSink> audio_sink_;
+  AudioRendererSink* audio_sink_;

[miu, 2016/05/12 21:53:06]

Please make this const: AudioRendererSink* const audio_sink_;

[o1ka, 2016/05/17 17:17:24]

Done.

+
+  // Callback to release the sink on mixer destruction.
+  const ReleaseSinkCallback release_sink_cb_;
 
   // Output parameters for this mixer.
   AudioParameters output_params_;