Update {virtual,override} to follow C++11 style in ppapi.

ppapi/proxy/flash_clipboard_resource.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_FLASH_CLIPBOARD_RESOURCE_H_
 #define PPAPI_PROXY_FLASH_CLIPBOARD_RESOURCE_H_
 
 #include "ppapi/proxy/connection.h"
 #include "ppapi/proxy/plugin_resource.h"
 #include "ppapi/shared_impl/flash_clipboard_format_registry.h"
 #include "ppapi/thunk/ppb_flash_clipboard_api.h"
 
 namespace ppapi {
 namespace proxy {
 
 class FlashClipboardResource
     : public PluginResource,
       public NON_EXPORTED_BASE(thunk::PPB_Flash_Clipboard_API) {
  public:
   FlashClipboardResource(Connection connection, PP_Instance instance);
-  virtual ~FlashClipboardResource();
+  ~FlashClipboardResource() override;
 
   // Resource implementation.
-  virtual thunk::PPB_Flash_Clipboard_API* AsPPB_Flash_Clipboard_API() override;
+  thunk::PPB_Flash_Clipboard_API* AsPPB_Flash_Clipboard_API() override;
 
   // PPB_Flash_Clipboard_API implementation.
-  virtual uint32_t RegisterCustomFormat(PP_Instance instance,
-                                        const char* format_name) override;
-  virtual PP_Bool IsFormatAvailable(PP_Instance instance,
-                                    PP_Flash_Clipboard_Type clipboard_type,
-                                    uint32_t format) override;
-  virtual PP_Var ReadData(PP_Instance instance,
-                          PP_Flash_Clipboard_Type clipboard_type,
-                          uint32_t format) override;
-  virtual int32_t WriteData(PP_Instance instance,
+  uint32_t RegisterCustomFormat(PP_Instance instance,
+                                const char* format_name) override;
+  PP_Bool IsFormatAvailable(PP_Instance instance,
                             PP_Flash_Clipboard_Type clipboard_type,
-                            uint32_t data_item_count,
-                            const uint32_t formats[],
-                            const PP_Var data_items[]) override;
-  virtual PP_Bool GetSequenceNumber(
+                            uint32_t format) override;
+  PP_Var ReadData(PP_Instance instance,
+                  PP_Flash_Clipboard_Type clipboard_type,
+                  uint32_t format) override;
+  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[]) override;
+  PP_Bool GetSequenceNumber(
       PP_Instance instance,
       PP_Flash_Clipboard_Type clipboard_type,
       uint64_t* sequence_number) override;
 
  private:
   FlashClipboardFormatRegistry clipboard_formats_;
 
   DISALLOW_COPY_AND_ASSIGN(FlashClipboardResource);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_FLASH_CLIPBOARD_RESOURCE_H_