Add GetSequenceNumber function to PPB_Flash_Clipboard

ppapi/thunk/ppb_flash_clipboard_api.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_THUNK_PPB_FLASH_CLIPBOARD_API_H_
 #define PPAPI_THUNK_PPB_FLASH_CLIPBOARD_API_H_
 
 #include "ppapi/c/private/ppb_flash_clipboard.h"
 #include "ppapi/shared_impl/singleton_resource_id.h"
 
@@ skipping 11 matching lines @@
                                     PP_Flash_Clipboard_Type clipboard_type,
                                     uint32_t format) = 0;
   virtual PP_Var ReadData(PP_Instance instance,
                           PP_Flash_Clipboard_Type clipboard_type,
                           uint32_t format) = 0;
   virtual int32_t WriteData(PP_Instance instance,
                             PP_Flash_Clipboard_Type clipboard_type,
                             uint32_t data_item_count,
                             const uint32_t formats[],
                             const PP_Var data_items[]) = 0;
+  virtual PP_Bool GetSequenceNumber(
+      PP_Instance instance,
+      PP_Flash_Clipboard_Type clipboard_type,
+      uint64_t* sequence_number) = 0;
 
   static const SingletonResourceID kSingletonResourceID =
       FLASH_CLIPBOARD_SINGLETON_ID;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif // PPAPI_THUNK_PPB_FLASH_CLIPBOARD_API_H_