Forward the number of skipped frames by the OS in audio playout.

media/audio/audio_output_device.cc

Index: media/audio/audio_output_device.cc
diff --git a/media/audio/audio_output_device.cc b/media/audio/audio_output_device.cc
index 9924f76b83e5e4e435a6f0a5598a22a68acad809..a0c6d4987093988f2973ee1f904a8277c335cc27 100644
--- a/media/audio/audio_output_device.cc
+++ b/media/audio/audio_output_device.cc
@@ -28,12 +28,17 @@ class AudioOutputDevice::AudioThreadCallback
   void MapSharedMemory() override;
 
   // Called whenever we receive notifications about pending data.
-  void Process(uint32 pending_data) override;
+  void Process(uint32_t pending_data, uint32_t frames_skipped) override;
 
  private:
   AudioRendererSink::RenderCallback* render_callback_;
   scoped_ptr<AudioBus> output_bus_;
   uint64 callback_num_;
+
+  // Stores the number of frames skipped by the consumer. Increased in
+  // FramesSkipped(). Used and cleared in Process().
+  uint32_t frames_skipped_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioThreadCallback);
 };
 
@@ -354,7 +359,7 @@ void AudioOutputDevice::OnStreamCreated(
     audio_callback_.reset(new AudioOutputDevice::AudioThreadCallback(
         audio_parameters_, handle, length, callback_));
     audio_thread_.Start(audio_callback_.get(), socket_handle,
-                        "AudioOutputDevice", true);
+                        "AudioOutputDevice", true, false);
     state_ = PAUSED;
 
     // We handle the case where Play() and/or Pause() may have been called
@@ -387,7 +392,8 @@ AudioOutputDevice::AudioThreadCallback::AudioThreadCallback(
     AudioRendererSink::RenderCallback* render_callback)
     : AudioDeviceThread::Callback(audio_parameters, memory, memory_length, 1),
       render_callback_(render_callback),
-      callback_num_(0) {}
+      callback_num_(0),
+      frames_skipped_(0) {}
 
 AudioOutputDevice::AudioThreadCallback::~AudioThreadCallback() {
 }
@@ -402,7 +408,8 @@ void AudioOutputDevice::AudioThreadCallback::MapSharedMemory() {
 }
 
 // Called whenever we receive notifications about pending data.
-void AudioOutputDevice::AudioThreadCallback::Process(uint32 pending_data) {
+void AudioOutputDevice::AudioThreadCallback::Process(uint32_t pending_data,
+                                                     uint32_t frames_skipped) {
   // Convert the number of pending bytes in the render buffer into milliseconds.
   int audio_delay_milliseconds = pending_data / bytes_per_ms_;
 
@@ -417,10 +424,12 @@ void AudioOutputDevice::AudioThreadCallback::Process(uint32 pending_data) {
     TRACE_EVENT_ASYNC_END0("audio", "StartingPlayback", this);
   }
 
-  // Update the audio-delay measurement then ask client to render audio.  Since
-  // |output_bus_| is wrapping the shared memory the Render() call is writing
-  // directly into the shared memory.
-  render_callback_->Render(output_bus_.get(), audio_delay_milliseconds);
+  // Update the audio-delay measurement, inform about the number of skipped
+  // frames, and ask client to render audio.  Since |output_bus_| is wrapping
+  // the shared memory the Render() call is writing directly into the shared
+  // memory.
+  render_callback_->Render(output_bus_.get(), audio_delay_milliseconds,
+                           frames_skipped);
 }
 
-}  // namespace media.
+}  // namespace media