Remove AudioDecoder from the Filter heirarchy.

media/base/pipeline.h

Index: media/base/pipeline.h
diff --git a/media/base/pipeline.h b/media/base/pipeline.h
index 771ccdf45f3bef62cebc5a3be7fe708970c28de6..f68377ba8f4817cd0c63488eb38f489a0f5f21e5 100644
--- a/media/base/pipeline.h
+++ b/media/base/pipeline.h
@@ -35,21 +35,6 @@ class MediaLog;
 class VideoDecoder;
 class VideoRenderer;
 
-// TODO(scherkus): this should be moved alongside host interface defintions.
-struct PipelineStatistics {
-  PipelineStatistics()
-      : audio_bytes_decoded(0),
-        video_bytes_decoded(0),
-        video_frames_decoded(0),
-        video_frames_dropped(0) {
-  }
-
-  uint32 audio_bytes_decoded;  // Should be uint64?
-  uint32 video_bytes_decoded;  // Should be uint64?
-  uint32 video_frames_decoded;
-  uint32 video_frames_dropped;
-};
-
 enum NetworkEvent {
   DOWNLOAD_CONTINUED,
   DOWNLOAD_PAUSED,
@@ -611,6 +596,7 @@ class MEDIA_EXPORT Pipeline
 
   // Reference to the filter(s) that constitute the pipeline.
   scoped_refptr<Filter> pipeline_filter_;
+  scoped_refptr<AudioDecoder> audio_decoder_;
 
   // Decoder reference used for signalling imminent shutdown.
   // This is a HACK necessary because WebMediaPlayerImpl::Destroy() holds the