Cleanup: Remove unneeded forward declarations in ppapi.

ppapi/proxy/ppb_font_proxy.h

 // Copyright (c) 2011 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_PPB_FONT_PROXY_H_
 #define PPAPI_PROXY_PPB_FONT_PROXY_H_
 
 #include "base/callback.h"
 #include "base/synchronization/waitable_event.h"
 #include "ppapi/proxy/interface_proxy.h"
 #include "ppapi/shared_impl/function_group_base.h"
 #include "ppapi/shared_impl/host_resource.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/shared_impl/webkit_forwarding.h"
 #include "ppapi/thunk/ppb_font_api.h"
 
 struct PPB_Font_Dev;
 
 namespace ppapi {
 namespace proxy {
 
-class SerializedVarReturnValue;
-
 class PPB_Font_Proxy : public InterfaceProxy,
                        public ppapi::thunk::PPB_Font_FunctionAPI {
  public:
-  PPB_Font_Proxy(Dispatcher* dispatcher);
+  explicit PPB_Font_Proxy(Dispatcher* dispatcher);
   virtual ~PPB_Font_Proxy();
 
   // FunctionGroupBase overrides.
   virtual ppapi::thunk::PPB_Font_FunctionAPI* AsPPB_Font_FunctionAPI() OVERRIDE;
 
   // PPB_Font_FunctionAPI implementation.
   virtual PP_Var GetFontFamilies(PP_Instance instance) OVERRIDE;
 
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
@@ skipping 49 matching lines @@
   // destruction).
   ppapi::WebKitForwarding::Font* font_forwarding_;
 
   DISALLOW_COPY_AND_ASSIGN(Font);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PPB_FONT_PROXY_H_