Caching AudioOutputDevice instances in mixer manager

media/base/audio_renderer_mixer.cc

Index: media/base/audio_renderer_mixer.cc
diff --git a/media/base/audio_renderer_mixer.cc b/media/base/audio_renderer_mixer.cc
index 10a19cded57347cfc31fc10a901050c680f671f6..c3a3000aa06b280e51f7521fdc4b5988d29e8917 100644
--- a/media/base/audio_renderer_mixer.cc
+++ b/media/base/audio_renderer_mixer.cc
@@ -15,9 +15,8 @@ namespace media {
 
 enum { kPauseDelaySeconds = 10 };
 
-AudioRendererMixer::AudioRendererMixer(
-    const AudioParameters& output_params,
-    const scoped_refptr<AudioRendererSink>& sink)
+AudioRendererMixer::AudioRendererMixer(const AudioParameters& output_params,

[miu, 2016/05/19 22:27:15]

nit: The order of args is opposite the order of the initialized data members. If
this is easy to fix (i.e., there aren't a ton of ctor calls to fix all over the
codebase), then please do.

[o1ka, 2016/05/23 16:16:55]

Done (another way around)

+                                       scoped_refptr<AudioRendererSink> sink)
     : audio_sink_(sink),

[miu, 2016/05/19 22:27:15]

std::move(sink)

[o1ka, 2016/05/23 16:16:54]

Done.

       output_params_(output_params),
       master_converter_(output_params, output_params, true),
@@ -25,12 +24,13 @@ AudioRendererMixer::AudioRendererMixer(
       last_play_time_(base::TimeTicks::Now()),
       // Initialize |playing_| to true since Start() results in an auto-play.
       playing_(true) {
+  DCHECK(audio_sink_);
   audio_sink_->Initialize(output_params, this);
   audio_sink_->Start();
 }
 
 AudioRendererMixer::~AudioRendererMixer() {
-  // AudioRendererSinks must be stopped before being destructed.
+  // AudioRendererSink must be stopped before mixer is destructed.
   audio_sink_->Stop();
 
   // Ensure that all mixer inputs have removed themselves prior to destruction.