content: Cleanup class/struct forward declarations

content/public/browser/browser_ppapi_host.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_PUBLIC_BROWSER_BROWSER_PPAPI_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_PPAPI_HOST_H_
 
 #include "base/callback_forward.h"
 #include "base/process/process.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/render_view_host.h"
 #include "ppapi/c/pp_instance.h"
 #include "url/gurl.h"
 
 namespace IPC {
 class ChannelProxy;
-struct ChannelHandle;
 class Sender;
 }
 
 namespace ppapi {
 class PpapiPermissions;
 namespace host {
 class PpapiHost;
 }
 }
 
@@ skipping 66 matching lines @@
   virtual GURL GetPluginURLForInstance(PP_Instance instance) = 0;
 
   // Sets a callback the BrowserPpapiHost will run when the plugin messages
   // that it is active.
   virtual void SetOnKeepaliveCallback(const OnKeepaliveCallback& callback) = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_PPAPI_HOST_H_