Introducing DecoderBuffer and general Buffer cleanup.

media/filters/ffmpeg_audio_decoder.h

Index: media/filters/ffmpeg_audio_decoder.h
diff --git a/media/filters/ffmpeg_audio_decoder.h b/media/filters/ffmpeg_audio_decoder.h
index 04739a263353599a57b8e4989a66e9c8754f8e93..5dbe8959722fc8d2b4d79fbc97c1a93e4fe75071 100644
--- a/media/filters/ffmpeg_audio_decoder.h
+++ b/media/filters/ffmpeg_audio_decoder.h
@@ -16,6 +16,7 @@ struct AVCodecContext;
 namespace media {
 
 class DataBuffer;
+class DecoderBuffer;
 
 class MEDIA_EXPORT FFmpegAudioDecoder : public AudioDecoder {
  public:
@@ -41,11 +42,11 @@ class MEDIA_EXPORT FFmpegAudioDecoder : public AudioDecoder {
                     const StatisticsCB& statistics_cb);
   void DoReset(const base::Closure& closure);
   void DoRead(const ReadCB& read_cb);
-  void DoDecodeBuffer(const scoped_refptr<Buffer>& input);
+  void DoDecodeBuffer(const scoped_refptr<DecoderBuffer>& input);
 
   // Reads from the demuxer stream with corresponding callback method.
   void ReadFromDemuxerStream();
-  void DecodeBuffer(const scoped_refptr<Buffer>& buffer);
+  void DecodeBuffer(const scoped_refptr<DecoderBuffer>& buffer);
 
   // Updates the output buffer's duration and timestamp based on the input
   // buffer. Will fall back to an estimated timestamp if the input lacks a