Enable round-tripping and updating of WebSourceBufferImpl timestamp offset

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 a87e128383b890fe14d1642a580f78ceab74afb8..c4f3bedef5fe09056c0f90f164f01ec47033ca1d 100644
--- a/media/filters/chunk_demuxer.h
+++ b/media/filters/chunk_demuxer.h
@@ -99,7 +99,11 @@ class MEDIA_EXPORT ChunkDemuxer : public Demuxer {
   Ranges<base::TimeDelta> GetBufferedRanges(const std::string& id) const;
 
   // Appends media data to the source buffer associated with |id|.
-  void AppendData(const std::string& id, const uint8* data, size_t length);
+  // If the append does not update the source buffer's timestamp offset,
+  // sets |*new_timestamp_offset| to kNoTimestamp(). Otherwise, sets it to the
+  // updated timestamp offset.
+  void AppendData(const std::string& id, const uint8* data, size_t length,
+                  base::TimeDelta* new_timestamp_offset);
 
   // Aborts parsing the current segment and reset the parser to a state where
   // it can accept a new segment.