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

media/audio/mac/audio_auhal_mac.cc

Index: media/audio/mac/audio_auhal_mac.cc
diff --git a/media/audio/mac/audio_auhal_mac.cc b/media/audio/mac/audio_auhal_mac.cc
index 39c4610495392cac6faa92da8ffb1e55c6b05656..1b73b9e1cf4792e5ddc2f1c99e01ffe9431da39b 100644
--- a/media/audio/mac/audio_auhal_mac.cc
+++ b/media/audio/mac/audio_auhal_mac.cc
@@ -53,6 +53,7 @@ AUHALStream::AUHALStream(AudioManagerMac* manager,
       hardware_latency_frames_(0),
       stopped_(true),
       current_hardware_pending_bytes_(0),
+      current_lost_frames_(0),
       last_sample_time_(0.0),
       last_number_of_frames_(0),
       total_lost_frames_(0),
@@ -204,7 +205,16 @@ OSStatus AUHALStream::Render(
     AudioBufferList* data) {
   TRACE_EVENT0("audio", "AUHALStream::Render");
 
-  UpdatePlayoutTimestamp(output_time_stamp);
+  UpdatePlayoutTimestampAndStats(output_time_stamp);
+
+  // Inform the source about any skipped (lost) frames. If we use a fifo this
+  // will be out of sync with the fifo pulls (different buffer sizes), so we do
+  // it here and not in ProvideInput().
+  if (lost_frames > 0) {
+    base::AutoLock auto_lock(source_lock_);
+    if (source_)
+      source_->OnSkippedData(lost_frames);
+  }
 
   // If the stream parameters change for any reason, we need to insert a FIFO
   // since the OnMoreData() pipeline can't handle frame size changes.
@@ -248,11 +258,11 @@ void AUHALStream::ProvideInput(int frame_delay, AudioBus* dest) {
   }
 
   // Supply the input data and render the output data.
-  source_->OnMoreData(
-      dest,
-      current_hardware_pending_bytes_ +
-      frame_delay * params_.GetBytesPerFrame());
+  source_->OnMoreData(dest, current_hardware_pending_bytes_ +
+                                frame_delay * params_.GetBytesPerFrame(),
+                      current_lost_frames_);
   dest->Scale(volume_);
+  current_lost_frames_ = 0;
 }
 
 // AUHAL callback.
@@ -346,7 +356,8 @@ double AUHALStream::GetPlayoutLatency(
   return (delay_frames + hardware_latency_frames_);
 }
 
-void AUHALStream::UpdatePlayoutTimestamp(const AudioTimeStamp* timestamp) {
+void AUHALStream::UpdatePlayoutTimestampAndStats(
+    const AudioTimeStamp* timestamp) {
   if ((timestamp->mFlags & kAudioTimeStampSampleTimeValid) == 0)
     return;
 
@@ -358,8 +369,9 @@ void AUHALStream::UpdatePlayoutTimestamp(const AudioTimeStamp* timestamp) {
       DCHECK_GT(diff, last_number_of_frames_);
       // We're being asked to render samples post what we expected. Update the
       // glitch count etc and keep a record of the largest glitch.
-      auto lost_frames = diff - last_number_of_frames_;
+      UInt32 lost_frames = diff - last_number_of_frames_;
       total_lost_frames_ += lost_frames;
+      current_lost_frames_ += lost_frames;
       if (lost_frames > largest_glitch_frames_)
         largest_glitch_frames_ = lost_frames;
       ++glitches_detected_;