content: Cleanup class/struct forward declarations

content/renderer/media/gpu/rtc_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 CONTENT_RENDERER_MEDIA_GPU_RTC_VIDEO_DECODER_H_
 #define CONTENT_RENDERER_MEDIA_GPU_RTC_VIDEO_DECODER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 15 matching lines @@
 #include "media/video/picture.h"
 #include "media/video/video_decode_accelerator.h"
 #include "third_party/webrtc/modules/video_coding/include/video_codec_interface.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace base {
 class WaitableEvent;
 };
 
 namespace media {
-class DecoderBuffer;
 class GpuVideoAcceleratorFactories;
 }
 
 namespace gpu {
 struct SyncToken;
 }
 
 namespace content {
 
 // This class uses hardware accelerated video decoder to decode video for
@@ skipping 252 matching lines @@
   // Must be destroyed, or invalidated, on the media thread.
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<RTCVideoDecoder> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RTCVideoDecoder);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_GPU_RTC_VIDEO_DECODER_H_