Express audio delay more precisely in frames rather than milliseconds.

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 dae8b7cd5e506ce5656a99230307d129d9d050dc..ad7044bc1c491019427c98f12fdf7357b81a0e74 100644
--- a/media/base/audio_renderer_mixer.h
+++ b/media/base/audio_renderer_mixer.h
@@ -58,7 +58,7 @@ class MEDIA_EXPORT AudioRendererMixer
 
   // AudioRendererSink::RenderCallback implementation.
   int Render(AudioBus* audio_bus,
-             uint32_t audio_delay_milliseconds,
+             uint32_t frames_delayed,
              uint32_t frames_skipped) override;
   void OnRenderError() override;
 
@@ -71,6 +71,7 @@ class MEDIA_EXPORT AudioRendererMixer
 
   // Output parameters for this mixer.
   AudioParameters output_params_;
+  double microseconds_per_frame_;
 
   // ---------------[ All variables below protected by |lock_| ]---------------
   base::Lock lock_;