content: Cleanup class/struct forward declarations

content/renderer/browser_plugin/browser_plugin_manager.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 CONTENT_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_MANAGER_H_
 #define CONTENT_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_MANAGER_H_
 
 #include "base/id_map.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "content/public/renderer/render_thread_observer.h"
 #include "ipc/ipc_sender.h"
 
-namespace blink {
-class WebFrame;
-}
-
 namespace content {
 
 class BrowserPlugin;
 class BrowserPluginDelegate;
 class RenderFrame;
 
 // BrowserPluginManager manages the routing of messages to the appropriate
 // BrowserPlugin object based on its instance ID. There is one BrowserPlugin
 // for the RenderThread.
 class CONTENT_EXPORT BrowserPluginManager : public RenderThreadObserver {
@@ skipping 38 matching lines @@
  private:
   // This map is keyed by guest instance IDs.
   IDMap<BrowserPlugin> instances_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserPluginManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_MANAGER_H_