Remove reference counting from media::DemuxerStream and friends.

media/base/audio_decoder.h

Index: media/base/audio_decoder.h
diff --git a/media/base/audio_decoder.h b/media/base/audio_decoder.h
index 743d1d4f77b6e5077dc66fcc332a2c3113343514..c88aab3d2ef5ed0569ccb303452bbb8d568e7e46 100644
--- a/media/base/audio_decoder.h
+++ b/media/base/audio_decoder.h
@@ -31,7 +31,7 @@ class MEDIA_EXPORT AudioDecoder {
   // Initialize an AudioDecoder with the given DemuxerStream, executing the
   // callback upon completion.
   // statistics_cb is used to update global pipeline statistics.
-  virtual void Initialize(const scoped_refptr<DemuxerStream>& stream,
+  virtual void Initialize(DemuxerStream* stream,
                           const PipelineStatusCB& status_cb,
                           const StatisticsCB& statistics_cb) = 0;