Expose MEDIA_STATISTICS stats to chrome://media-internals.

media/base/media_log_event.h

Index: media/base/media_log_event.h
diff --git a/media/base/media_log_event.h b/media/base/media_log_event.h
index 9b0f6e1d96137c8f71bcdfcf7febe824807f7f06..11ef5a0c44688ee6295049f8f14042ece5807c44 100644
--- a/media/base/media_log_event.h
+++ b/media/base/media_log_event.h
@@ -72,6 +72,13 @@ struct MediaLogEvent {
     // Errors reported by Media Source Extensions code.
     MEDIA_SOURCE_ERROR,
     // params: "error": Error string describing the error detected.
+
+   // Statistics for pipeline.
+   // params: "decoded_audio_bytes": <decoded audio bytes of the video>
+   //         "decoded_video_bytes": <decoded video bytes of the video>
+   //         "decoded_video_frames": <decoded video frames of the video>
+   //         "dropped_video_frames": <dropped video frames of the video>
+   PIPELINE_STATISTICS_CHANGED,
   };
 
   int32 id;