Caching AudioOutputDevice instances in mixer manager

media/base/fake_audio_renderer_sink.h

Index: media/base/fake_audio_renderer_sink.h
diff --git a/media/base/fake_audio_renderer_sink.h b/media/base/fake_audio_renderer_sink.h
index 85834722d4cf898ee5b875f9f49a00388502cf32..bc9928bd82933f4f9755929b61b84e0042c4bf11 100644
--- a/media/base/fake_audio_renderer_sink.h
+++ b/media/base/fake_audio_renderer_sink.h
@@ -29,6 +29,8 @@ class FakeAudioRendererSink : public AudioRendererSink {
 
   FakeAudioRendererSink();
 
+  explicit FakeAudioRendererSink(const AudioParameters& hardware_params);
+
   void Initialize(const AudioParameters& params,
                   RenderCallback* callback) override;
   void Start() override;