More header cleanup:

media/base/filters.h

 // Copyright (c) 2010 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.
 
 // Filters are connected in a strongly typed manner, with downstream filters
 // always reading data from upstream filters.  Upstream filters have no clue
 // who is actually reading from them, and return the results via callbacks.
 //
 //                         DemuxerStream(Video) <- VideoDecoder <- VideoRenderer
 // DataSource <- Demuxer <
@@ skipping 13 matching lines @@
 #define MEDIA_BASE_FILTERS_H_
 
 #include <limits>
 #include <string>
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/ref_counted.h"
 #include "base/time.h"
+#include "base/scoped_ptr.h"
 #include "media/base/media_format.h"
 
 namespace media {
 
 class Buffer;
 class Decoder;
 class DemuxerStream;
 class FilterHost;
 class VideoFrame;
 class WritableBuffer;
@@ skipping 329 matching lines @@
   // buffer.
   virtual bool HasEnded() = 0;
 
   // Sets the output volume.
   virtual void SetVolume(float volume) = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_FILTERS_H_