ppapi: Cleanup class/struct forward declarations

ppapi/proxy/resource_creation_proxy.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 PPAPI_PROXY_RESOURCE_CREATION_PROXY_H_
 #define PPAPI_PROXY_RESOURCE_CREATION_PROXY_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "ipc/ipc_channel.h"
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/proxy/interface_proxy.h"
 #include "ppapi/proxy/serialized_structs.h"
 #include "ppapi/thunk/resource_creation_api.h"
 
 struct PP_Size;
 
 namespace ppapi {
 
-class HostResource;
-
 namespace proxy {
 
 struct Connection;
 class Dispatcher;
 
 class ResourceCreationProxy : public InterfaceProxy,
                               public thunk::ResourceCreationAPI {
  public:
   explicit ResourceCreationProxy(Dispatcher* dispatcher);
   ~ResourceCreationProxy() override;
@@ skipping 154 matching lines @@
 
  private:
   Connection GetConnection();
   DISALLOW_COPY_AND_ASSIGN(ResourceCreationProxy);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_RESOURCE_CREATION_PROXY_H_