MSE: Log a warning if muxed AV media segment has no A or has no V block

media/filters/media_source_state.h

Index: media/filters/media_source_state.h
diff --git a/media/filters/media_source_state.h b/media/filters/media_source_state.h
index 4ec83254d02abedda76e64bed84e47d1c36ac118..8d41b1ee0f1a52bbde87ec23987440ca6f893eb5 100644
--- a/media/filters/media_source_state.h
+++ b/media/filters/media_source_state.h
@@ -152,6 +152,10 @@ class MEDIA_EXPORT MediaSourceState {
   // (and therefore before parsing is performed) to prepare space for new data.
   size_t EstimateVideoDataSize(size_t muxed_data_chunk_size) const;
 
+  // Tracks the number of MEDIA_LOGs emitted for segments missing expected audio
+  // or video blocks. Useful to prevent log spam.
+  int num_missing_track_logs_ = 0;
+
   CreateDemuxerStreamCB create_demuxer_stream_cb_;
   NewTextTrackCB new_text_track_cb_;
 
@@ -180,6 +184,12 @@ class MEDIA_EXPORT MediaSourceState {
   // Keeps track of whether a media segment is being parsed.
   bool parsing_media_segment_;
 
+  // Valid only while |parsing_media_segment_| is true. These flags enable
+  // warning when at least one frame for each A/V track is not in a parsed media
+  // segment.
+  bool media_segment_contained_audio_frame_;
+  bool media_segment_contained_video_frame_;
+
   // The object used to parse appended data.
   scoped_ptr<StreamParser> stream_parser_;