Change DemuxerStream::ReadCallback to use ref-counted buffers.

media/filters/ffmpeg_audio_decoder.cc

Index: media/filters/ffmpeg_audio_decoder.cc
diff --git a/media/filters/ffmpeg_audio_decoder.cc b/media/filters/ffmpeg_audio_decoder.cc
index f2ac089bfca2ce3fae526b6ac4cfc858a2c278d6..3a0ab344641e9d4f279858075b00befac52782bc 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -250,13 +250,10 @@ void FFmpegAudioDecoder::ReadFromDemuxerStream() {
   demuxer_stream_->Read(base::Bind(&FFmpegAudioDecoder::DecodeBuffer, this));
 }
 
-void FFmpegAudioDecoder::DecodeBuffer(Buffer* buffer) {
-  // TODO(scherkus): change DemuxerStream::Read() to use scoped_refptr<> for
-  // callback.
-  scoped_refptr<Buffer> ref_buffer(buffer);
+void FFmpegAudioDecoder::DecodeBuffer(const scoped_refptr<Buffer>& buffer) {
   message_loop_->PostTask(
       FROM_HERE,
-      base::Bind(&FFmpegAudioDecoder::DoDecodeBuffer, this, ref_buffer));
+      base::Bind(&FFmpegAudioDecoder::DoDecodeBuffer, this, buffer));
 }
 
 void FFmpegAudioDecoder::UpdateDurationAndTimestamp(