MSE: Protect better against reaching HAVE_METADATA too early

media/filters/chunk_demuxer.h

Index: media/filters/chunk_demuxer.h
diff --git a/media/filters/chunk_demuxer.h b/media/filters/chunk_demuxer.h
index fa7540dc4d5dcfa26bcba41b805d0e33019e0c7a..969afb22239ec0aa4fd240b781064ece24321651 100644
--- a/media/filters/chunk_demuxer.h
+++ b/media/filters/chunk_demuxer.h
@@ -381,6 +381,10 @@ class MEDIA_EXPORT ChunkDemuxer : public Demuxer {
   scoped_ptr<ChunkDemuxerStream> audio_;
   scoped_ptr<ChunkDemuxerStream> video_;
 
+  // Counter to ensure that we do not transition too early to INITIALIZED.
+  // Incremented in AddId(), decremented in OnSourceInitDone().
+  int pending_source_init_done_count_;
+
   base::TimeDelta duration_;
 
   // The duration passed to the last SetDuration(). If