media: Cleanup class/struct forward declarations

media/filters/fake_video_decoder.h

 // Copyright 2013 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_FILTERS_FAKE_VIDEO_DECODER_H_
 #define MEDIA_FILTERS_FAKE_VIDEO_DECODER_H_
 
 #include <stddef.h>
 
 #include <list>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/callback_holder.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/pipeline_status.h"
 #include "media/base/video_decoder.h"
 #include "media/base/video_decoder_config.h"
 #include "media/base/video_frame.h"
 #include "ui/gfx/geometry/size.h"
 
 using base::ResetAndReturn;
 
-namespace base {
-class SingleThreadTaskRunner;
-}
-
 namespace media {
 
 typedef base::Callback<void(int)> BytesDecodedCB;
 
 class FakeVideoDecoder : public VideoDecoder {
  public:
   // Constructs an object with a decoding delay of |decoding_delay| frames.
   // |bytes_decoded_cb| is called after each decode. The sum of the byte
   // count over all calls will be equal to total_bytes_decoded().
   FakeVideoDecoder(int decoding_delay,
@@ skipping 81 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<FakeVideoDecoder> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeVideoDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FAKE_VIDEO_DECODER_H_