Add config change handling to SourceBufferStream & ChunkDemuxer

media/base/video_decoder_config.h

Index: media/base/video_decoder_config.h
diff --git a/media/base/video_decoder_config.h b/media/base/video_decoder_config.h
index e095ba9f4889b23b39f56acc466d94ccf0da4149..894eb241437b66f28e5a9cf53fedf0ffa9c76e93 100644
--- a/media/base/video_decoder_config.h
+++ b/media/base/video_decoder_config.h
@@ -96,6 +96,10 @@ class MEDIA_EXPORT VideoDecoderConfig {
   // otherwise.
   bool IsValidConfig() const;
 
+  // Returns true if all fields in |config| match this config.
+  // Note: The contents of |extra_data_| are compared not the raw pointers.
+  bool Matches(const VideoDecoderConfig& config) const;
+
   // Returns a human-readable string describing |*this|.  For debugging & test
   // output only.
   std::string AsHumanReadableString() const;