Pepper/Flapper: Add IsFormatAvailable() to PPB_Flash_Clipboard.

ppapi/proxy/ppb_flash_clipboard_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_FLASH_CLIPBOARD_PROXY_H_
 #define PPAPI_PROXY_PPB_FLASH_CLIPBOARD_PROXY_H_
 
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/proxy/interface_proxy.h"
 
@@ skipping 15 matching lines @@
 
   const PPB_Flash_Clipboard* ppb_flash_clipboard_target() const {
     return reinterpret_cast<const PPB_Flash_Clipboard*>(target_interface());
   }
 
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);
 
  private:
   // Message handlers.
+  void OnMsgIsFormatAvailable(PP_Instance instance_id,
+                              int clipboard_type,
+                              int format,
+                              bool* result);
   void OnMsgReadPlainText(PP_Instance instance_id,
                           int clipboard_type,
                           SerializedVarReturnValue result);
   void OnMsgWritePlainText(PP_Instance instance_id,
                            int clipboard_type,
                            SerializedVarReceiveInput text);
 };
 
 }  // namespace proxy
 }  // namespace pp
 
 #endif  // PPAPI_PROXY_PPB_FLASH_CLIPBOARD_PROXY_H_