Fixed track id remapping in MSE FrameProcessor

media/filters/frame_processor.h

Index: media/filters/frame_processor.h
diff --git a/media/filters/frame_processor.h b/media/filters/frame_processor.h
index 69a313efaff36dc144cf03f4b11eb5623fdc8163..dd28bad83d0d4a5cc156154e7a6f146132a56175 100644
--- a/media/filters/frame_processor.h
+++ b/media/filters/frame_processor.h
@@ -58,12 +58,15 @@ class MEDIA_EXPORT FrameProcessor {
   // frames for the track |id| to |stream|.
   bool AddTrack(StreamParser::TrackId id, ChunkDemuxerStream* stream);
 
-  // Updates the internal mapping of TrackId to track buffer for the track
-  // buffer formerly associated with |old_id| to be associated with |new_id|.
-  // Returns false to indicate failure due to either no existing track buffer
-  // for |old_id| or collision with previous track buffer already mapped to
-  // |new_id|. Otherwise returns true.
-  bool UpdateTrack(StreamParser::TrackId old_id, StreamParser::TrackId new_id);
+  // A map that describes how track ids changed between init segment. Maps the
+  // old track id for a new track id for the same track.
+  using TrackIdChanges = std::map<StreamParser::TrackId, StreamParser::TrackId>;
+
+  // Updates the internal mapping of TrackIds to track buffers. The input
+  // parameter |track_id_changes| maps old track ids to new ones. The track ids
+  // not present in the map must be assumed unchanged. Returns false if
+  // remapping failed.
+  bool UpdateTrackIds(const TrackIdChanges& track_id_changes);
 
   // Sets the need random access point flag on all track buffers to true.
   void SetAllTrackBuffersNeedRandomAccessPoint();
@@ -123,8 +126,9 @@ class MEDIA_EXPORT FrameProcessor {
                     base::TimeDelta* timestamp_offset);
 
   // TrackId-indexed map of each track's stream.
-  std::map<StreamParser::TrackId, std::unique_ptr<MseTrackBuffer>>
-      track_buffers_;
+  using TrackBuffersMap =
+      std::map<StreamParser::TrackId, std::unique_ptr<MseTrackBuffer>>;
+  TrackBuffersMap track_buffers_;
 
   // The last audio buffer seen by the frame processor that was removed because
   // it was entirely before the start of the append window.