Remove AudioDecoder from the Filter heirarchy.

media/base/filter_collection.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_FILTER_COLLECTION_H_
 #define MEDIA_BASE_FILTER_COLLECTION_H_
 
 #include <list>
 
 #include "base/memory/ref_counted.h"
+#include "media/base/audio_decoder.h"
 #include "media/base/demuxer_factory.h"
 #include "media/base/filters.h"
 
 namespace media {
 
 // This is a collection of Filter objects used to form a media playback
 // pipeline. See src/media/base/pipeline.h for more information.
 class MEDIA_EXPORT FilterCollection {
  public:
   FilterCollection();
   ~FilterCollection();
 
   // DemuxerFactory accessor methods.
   void SetDemuxerFactory(scoped_ptr<DemuxerFactory> factory);
   DemuxerFactory* GetDemuxerFactory();
 
   // Adds a filter to the collection.
   void AddVideoDecoder(VideoDecoder* filter);
-  void AddAudioDecoder(AudioDecoder* filter);
+  void AddAudioDecoder(AudioDecoder* audio_decoder);
   void AddVideoRenderer(VideoRenderer* filter);
   void AddAudioRenderer(AudioRenderer* filter);
 
   // Is the collection empty?
   bool IsEmpty() const;
 
   // Remove remaining filters.
   void Clear();
 
   // Selects a filter of the specified type from the collection.
   // If the required filter cannot be found, NULL is returned.
   // If a filter is returned it is removed from the collection.
   // Filters are selected in FIFO order.
   void SelectVideoDecoder(scoped_refptr<VideoDecoder>* filter_out);
-  void SelectAudioDecoder(scoped_refptr<AudioDecoder>* filter_out);
+  void SelectAudioDecoder(scoped_refptr<AudioDecoder>* out);
   void SelectVideoRenderer(scoped_refptr<VideoRenderer>* filter_out);
   void SelectAudioRenderer(scoped_refptr<AudioRenderer>* filter_out);
 
  private:
   // Identifies the type of filter implementation. Each filter has to be one of
   // the following types. This is used to mark, identify, and support
   // downcasting of different filter types stored in the filters_ list.
   enum FilterType {
-    AUDIO_DECODER,
     VIDEO_DECODER,
     AUDIO_RENDERER,
     VIDEO_RENDERER,
   };
 
   // List of filters managed by this collection.
   typedef std::pair<FilterType, scoped_refptr<Filter> > FilterListElement;
   typedef std::list<FilterListElement> FilterList;
   FilterList filters_;
   scoped_ptr<DemuxerFactory> demuxer_factory_;
+  std::list<scoped_refptr<AudioDecoder> > audio_decoders_;
 
   // Helper function that adds a filter to the filter list.
   void AddFilter(FilterType filter_type, Filter* filter);
 
   // Helper function for SelectXXX() methods. It manages the
   // downcasting and mapping between FilterType and Filter class.
   template<FilterType filter_type, typename F>
   void SelectFilter(scoped_refptr<F>* filter_out);
 
   // Helper function that searches the filters list for a specific filter type.
   void SelectFilter(FilterType filter_type, scoped_refptr<Filter>* filter_out);
 
   DISALLOW_COPY_AND_ASSIGN(FilterCollection);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_FILTER_COLLECTION_H_