Cleanup: Remove unneeded forward declarations in ppapi.

ppapi/proxy/ppb_file_chooser_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_FILE_CHOOSER_PROXY_H_
 #define PPAPI_PROXY_PPB_FILE_CHOOSER_PROXY_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/cpp/completion_callback.h"
 #include "ppapi/proxy/interface_proxy.h"
 #include "ppapi/proxy/proxy_non_thread_safe_ref_count.h"
 #include "ppapi/thunk/ppb_file_chooser_api.h"
 
 struct PPB_FileChooser_Dev;
 struct PPB_FileChooserTrusted;
 
 namespace ppapi {
 
 class HostResource;
 struct PPB_FileRef_CreateInfo;
 
 namespace proxy {
 
-class SerializedVarReceiveInput;
-
 class PPB_FileChooser_Proxy : public InterfaceProxy {
  public:
-  PPB_FileChooser_Proxy(Dispatcher* dispatcher);
+  explicit PPB_FileChooser_Proxy(Dispatcher* dispatcher);
   virtual ~PPB_FileChooser_Proxy();
 
   static const Info* GetTrustedInfo();
 
   static PP_Resource CreateProxyResource(
       PP_Instance instance,
       PP_FileChooserMode_Dev mode,
       const char* accept_mime_types);
 
   // InterfaceProxy implementation.
@@ skipping 25 matching lines @@
   pp::CompletionCallbackFactory<PPB_FileChooser_Proxy,
                                 ProxyNonThreadSafeRefCount> callback_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_FileChooser_Proxy);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PPB_FILE_CHOOSER_PROXY_H_