Add config change handling to SourceBufferStream & ChunkDemuxer

media/base/audio_decoder_config.h

Index: media/base/audio_decoder_config.h
diff --git a/media/base/audio_decoder_config.h b/media/base/audio_decoder_config.h
index 6e58c5b407896d746d67f5f111e33bccf234192b..e2309d5fb5cb52b444249b8a8a8d7234115c1cbd 100644
--- a/media/base/audio_decoder_config.h
+++ b/media/base/audio_decoder_config.h
@@ -65,6 +65,10 @@ class MEDIA_EXPORT AudioDecoderConfig {
   // 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 AudioDecoderConfig& config) const;
+
   AudioCodec codec() const;
   int bits_per_channel() const;
   ChannelLayout channel_layout() const;