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

ppapi/proxy/flash_fullscreen_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_FULLSCREEN_RESOURCE_H_
 #define PPAPI_PROXY_FLASH_FULLSCREEN_RESOURCE_H_
 
 #include "ppapi/proxy/connection.h"
 #include "ppapi/proxy/plugin_resource.h"
 #include "ppapi/thunk/ppb_flash_fullscreen_api.h"
 
 namespace ppapi {
 namespace proxy {
 
 class FlashFullscreenResource
     : public PluginResource,
       public thunk::PPB_Flash_Fullscreen_API {
  public:
   FlashFullscreenResource(Connection connection,
                           PP_Instance instance);
-  virtual ~FlashFullscreenResource();
+  ~FlashFullscreenResource() override;
 
   // Resource overrides.
-  virtual thunk::PPB_Flash_Fullscreen_API*
-      AsPPB_Flash_Fullscreen_API() override;
+  thunk::PPB_Flash_Fullscreen_API* AsPPB_Flash_Fullscreen_API() override;
 
   // PPB_Flash_Fullscreen_API implementation.
-  virtual PP_Bool IsFullscreen(PP_Instance instance) override;
-  virtual PP_Bool SetFullscreen(PP_Instance instance,
-                                PP_Bool fullscreen) override;
-  virtual void SetLocalIsFullscreen(PP_Instance instance,
-                                    PP_Bool is_fullscreen) override;
+  PP_Bool IsFullscreen(PP_Instance instance) override;
+  PP_Bool SetFullscreen(PP_Instance instance, PP_Bool fullscreen) override;
+  void SetLocalIsFullscreen(PP_Instance instance,
+                            PP_Bool is_fullscreen) override;
 
  private:
   PP_Bool is_fullscreen_;
 
   DISALLOW_COPY_AND_ASSIGN(FlashFullscreenResource);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_FLASH_FULLSCREEN_RESOURCE_H_