Mixing audio with different latency requirements

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 68f7aec1e2a72972704d3d71753d81802187a137..1d5afb475ce2f591d0ba0f6c205222ed55036af1 100644
--- a/media/base/audio_renderer_mixer.h
+++ b/media/base/audio_renderer_mixer.h
@@ -27,7 +27,8 @@ class MEDIA_EXPORT AudioRendererMixer
     : NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
  public:
   AudioRendererMixer(const AudioParameters& output_params,
-                     scoped_refptr<AudioRendererSink> sink);
+                     scoped_refptr<AudioRendererSink> sink,
+                     const std::string& uma_histogram);
   ~AudioRendererMixer() override;
 
   // Add or remove a mixer input from mixing; called by AudioRendererMixerInput.
@@ -48,7 +49,11 @@ class MEDIA_EXPORT AudioRendererMixer
 
   OutputDeviceInfo GetOutputDeviceInfo();
 
+  AudioParameters GetOutputParamsForTesting() { return output_params_; };

[tommi (sloooow) - chröme, 2016/06/28 14:14:54]

nit: const&

[o1ka, 2016/06/29 10:11:26]

Done.

+
  private:
+  class UMAMaxValueTracker;
+
   // Maps input sample rate to the dedicated converter.
   using AudioConvertersMap =
       std::map<int, std::unique_ptr<LoopbackAudioConverter>>;
@@ -91,6 +96,10 @@ class MEDIA_EXPORT AudioRendererMixer
   base::TimeTicks last_play_time_;
   bool playing_;
 
+  // Tracks the maximum number of simultaneous mixer inputs and logs it into
+  // UMA histogram upon the destruction.
+  std::unique_ptr<UMAMaxValueTracker> input_count_tracker_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioRendererMixer);
 };