remoting: Cleanup class/struct fwd declarations

remoting/protocol/webrtc_frame_scheduler.h

 // Copyright 2016 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 REMOTING_PROTOCOL_WEBRTC_FRAME_SCHEDULER_H_
 #define REMOTING_PROTOCOL_WEBRTC_FRAME_SCHEDULER_H_
 
 #include "base/callback_forward.h"
 #include "base/memory/weak_ptr.h"
 #include "remoting/codec/webrtc_video_encoder.h"
 #include "third_party/webrtc/video_encoder.h"
 
 namespace remoting {
 namespace protocol {
 
 struct HostFrameStats;
-class VideoChannelStateObserver;
 class WebrtcDummyVideoEncoderFactory;
 
 // An abstract interface for frame schedulers, which are responsible for
 // scheduling when video frames are captured and for defining encoding
 // parameters for each frame.
 class WebrtcFrameScheduler {
  public:
   WebrtcFrameScheduler() {}
   virtual ~WebrtcFrameScheduler() {}
 
@@ skipping 18 matching lines @@
   virtual void OnFrameEncoded(
       const WebrtcVideoEncoder::EncodedFrame& encoded_frame,
       const webrtc::EncodedImageCallback::Result& send_result,
       HostFrameStats* frame_stats) = 0;
 };
 
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_WEBRTC_FRAME_SCHEDULER_H_