chrome: Cleanup class/struct forward declarations

chrome/renderer/media/cast_receiver_session.h

 // Copyright 2015 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 CHROME_RENDERER_MEDIA_CAST_RECEIVER_SESSION_H_
 #define CHROME_RENDERER_MEDIA_CAST_RECEIVER_SESSION_H_
 
 #include <memory>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
 #include "chrome/renderer/media/cast_receiver_session_delegate.h"
 
-namespace blink {
-class WebMediaStream;
-}
-
 namespace media {
 class AudioCapturerSource;
 struct VideoCaptureFormat;
 class VideoCapturerSource;
 }
 
 namespace net {
 class IPEndPoint;
 }
 
@@ skipping 42 matching lines @@
   media::cast::FrameReceiverConfig audio_config_;
   media::cast::FrameReceiverConfig video_config_;
   std::unique_ptr<CastReceiverSessionDelegate> delegate_;
   const scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
   media::VideoCaptureFormat format_;
 
   DISALLOW_COPY_AND_ASSIGN(CastReceiverSession);
 };
 
 #endif // CHROME_RENDERER_MEDIA_CAST_RECEIVER_SESSION_H_