media: Cleanup class/struct forward declarations

media/audio/virtual_audio_input_stream.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_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_
 #define MEDIA_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <set>
 
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/fake_audio_worker.h"
 #include "media/base/audio_converter.h"
 #include "media/base/audio_parameters.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace media {
 
 class LoopbackAudioConverter;
-class VirtualAudioOutputStream;
 
 // VirtualAudioInputStream converts and mixes audio from attached
 // VirtualAudioOutputStreams into a single stream. It will continuously render
 // audio until this VirtualAudioInputStream is stopped and closed.
 class MEDIA_EXPORT VirtualAudioInputStream : public AudioInputStream {
  public:
   // Callback invoked just after VirtualAudioInputStream is closed.
   typedef base::Callback<void(VirtualAudioInputStream* vais)>
       AfterCloseCallback;
 
@@ skipping 71 matching lines @@
   std::unique_ptr<AudioBus> audio_bus_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(VirtualAudioInputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_