content: Cleanup class/struct forward declarations

content/renderer/media/peer_connection_tracker.h

 // Copyright (c) 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_PEER_CONNECTION_TRACKER_H_
 #define CONTENT_RENDERER_MEDIA_PEER_CONNECTION_TRACKER_H_
 
 #include <map>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "content/public/renderer/render_thread_observer.h"
 #include "ipc/ipc_platform_file.h"
 #include "third_party/WebKit/public/platform/WebMediaStream.h"
 #include "third_party/WebKit/public/platform/WebRTCPeerConnectionHandlerClient.h"
 #include "third_party/WebKit/public/platform/WebRTCSessionDescription.h"
 #include "third_party/webrtc/api/peerconnectioninterface.h"
 
 namespace blink {
 class WebFrame;
 class WebMediaConstraints;
 class WebRTCAnswerOptions;
 class WebRTCICECandidate;
 class WebRTCOfferOptions;
-class WebString;
 class WebRTCSessionDescription;
 class WebUserMediaRequest;
 }  // namespace blink
 
 namespace webrtc {
 class DataChannelInterface;
 }  // namespace webrtc
 
 namespace content {
 class RTCPeerConnectionHandler;
@@ skipping 181 matching lines @@
   int next_local_id_;
   base::ThreadChecker main_thread_;
   RenderThread* send_target_for_test_;
 
   DISALLOW_COPY_AND_ASSIGN(PeerConnectionTracker);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_PEER_CONNECTION_TRACKER_H_