Clean up forward declarations in Source/web

Source/web/InspectorClientImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 20 matching lines @@
 #ifndef InspectorClientImpl_h
 #define InspectorClientImpl_h
 
 #include "core/inspector/InspectorClient.h"
 #include "core/inspector/InspectorController.h"
 #include "core/inspector/InspectorFrontendChannel.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
-class WebDevToolsAgentClient;
 class WebDevToolsAgentImpl;
 class WebViewImpl;
 
 class InspectorClientImpl final : public InspectorClient, public InspectorFrontendChannel {
 public:
     explicit InspectorClientImpl(WebViewImpl*);
     virtual ~InspectorClientImpl();
 
     // InspectorClient methods:
     virtual void highlight() override;
@@ skipping 36 matching lines @@
 private:
     WebDevToolsAgentImpl* devToolsAgent();
 
     // The WebViewImpl of the page being inspected; gets passed to the constructor
     WebViewImpl* m_inspectedWebView;
 };
 
 } // namespace blink
 
 #endif