Feed the WebRTC APM with empty far-end frames for the number of frames skipped by OS.

content/renderer/media/webrtc_audio_renderer.h

Index: content/renderer/media/webrtc_audio_renderer.h
diff --git a/content/renderer/media/webrtc_audio_renderer.h b/content/renderer/media/webrtc_audio_renderer.h
index ee0d48945b6bec7905438214519de15183e127cf..9dc58aaf6ce9657e19d445d9f165997a9fa99c64 100644
--- a/content/renderer/media/webrtc_audio_renderer.h
+++ b/content/renderer/media/webrtc_audio_renderer.h
@@ -240,6 +240,10 @@ class CONTENT_EXPORT WebRtcAudioRenderer
   // Delay due to the FIFO in milliseconds.
   int fifo_delay_milliseconds_;
 
+  // Contains the accumulated number of skipped frames which is provided to the
+  // WebRTC AEC. Accessed on audio render thread.
+  uint32_t skipped_frames_;
+
   base::TimeDelta current_time_;
 
   // Saved volume and playing state of the root renderer.