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..cdc9334180ed14f81abbce7f37fe51e5c3652566 100644
--- a/media/audio/audio_output_device.cc
+++ b/media/audio/audio_output_device.cc
@@ -28,12 +28,19 @@ 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) override;
+
+  void FramesSkipped(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. Used and cleared in
+  // Process().

[tommi (sloooow) - chröme, 2015/12/01 13:34:26]

nit: and modified in FramesSkipped

[Henrik Grunell, 2015/12/03 17:01:07]

Done.

+  uint32_t frames_skipped_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioThreadCallback);
 };
 
@@ -354,7 +361,7 @@ 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 +394,8 @@ 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 +410,7 @@ 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) {
   // Convert the number of pending bytes in the render buffer into milliseconds.
   int audio_delay_milliseconds = pending_data / bytes_per_ms_;
 
@@ -417,10 +425,21 @@ void AudioOutputDevice::AudioThreadCallback::Process(uint32 pending_data) {
     TRACE_EVENT_ASYNC_END0("audio", "StartingPlayback", this);
   }
 
+  // Inform about skipped frames if any.
+  if (frames_skipped_ > 0) {
+    render_callback_->OnFramesSkipped(frames_skipped_);
+    frames_skipped_ = 0;
+  }
+
   // 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);
 }
 
+void AudioOutputDevice::AudioThreadCallback::FramesSkipped(

[tommi (sloooow) - chröme, 2015/12/01 13:34:25]

thread check (must be on the same thread as Process is called on)

[Henrik Grunell, 2015/12/03 17:01:07]

The contract with AudioDeviceThread is that all callbacks will run on the same
thread. (See ADT class comment.) I can still add a thread check  of course.
Better safe than sorry?

+    uint32_t frames_skipped) {
+  frames_skipped_ += frames_skipped;
+}
+
 }  // namespace media.