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

media/audio/audio_output_controller.h

Index: media/audio/audio_output_controller.h
diff --git a/media/audio/audio_output_controller.h b/media/audio/audio_output_controller.h
index 7820665440b4e0316e8d66a8fcfcdaade1d302db..54e5b029182090efb988b50295a3f2cdf1d4935d 100644
--- a/media/audio/audio_output_controller.h
+++ b/media/audio/audio_output_controller.h
@@ -82,8 +82,12 @@ class MEDIA_EXPORT AudioOutputController
 
     // Notify the synchronous reader the number of bytes in the
     // AudioOutputController not yet played. This is used by SyncReader to
-    // prepare more data and perform synchronization.
-    virtual void UpdatePendingBytes(uint32 bytes) = 0;
+    // prepare more data and perform synchronization. Also inform about if any
+    // frames has been skipped by the consumer. The source can handle this
+    // appropriately depending on the type of source. An ordinary file playout
+    // would ignore this.
+    virtual void UpdatePendingBytes(uint32_t bytes,
+                                    uint32_t frames_skipped) = 0;
 
     // Attempts to completely fill |dest|, zeroing |dest| if the request can not
     // be fulfilled (due to timeout).
@@ -154,6 +158,7 @@ class MEDIA_EXPORT AudioOutputController
 
   // AudioSourceCallback implementation.
   int OnMoreData(AudioBus* dest, uint32 total_bytes_delay) override;
+  void OnSkippedData(uint32 frames_skipped) override;
   void OnError(AudioOutputStream* stream) override;
 
   // AudioDeviceListener implementation.  When called AudioOutputController will
@@ -258,6 +263,10 @@ class MEDIA_EXPORT AudioOutputController
   bool ignore_errors_during_stop_close_;
   base::Lock error_lock_;
 
+  // Stores the number of skipped frames reported in OnSkippedData(), passed on
+  // to the provider in OnMoreData().
+  uint32_t frames_skipped_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioOutputController);
 };