Updated the sync module with a slow moving filter

Review URL: https://webrtc-codereview.appspot.com/1326008

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3884 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/video_engine/stream_synchronization.h b/video_engine/stream_synchronization.h
index 9b7780c..f057b76 100644
--- a/video_engine/stream_synchronization.h
+++ b/video_engine/stream_synchronization.h
@@ -52,6 +52,7 @@
   int audio_channel_id_;
   int video_channel_id_;
   int base_target_delay_ms_;
+  int avg_diff_ms_;
 };
 }  // namespace webrtc