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

ppapi/proxy/browser_font_singleton_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_BROWSER_FONT_SINGLETON_RESOURCE_H_
 #define PPAPI_PROXY_BROWSER_FONT_SINGLETON_RESOURCE_H_
 
 #include "ppapi/proxy/connection.h"
 #include "ppapi/proxy/plugin_resource.h"
 #include "ppapi/thunk/ppb_browser_font_singleton_api.h"
 
 namespace ppapi {
 namespace proxy {
 
 // This handles the singleton calls (that don't take a PP_Resource parameter)
 // on the browser font interface
 class BrowserFontSingletonResource
     : public PluginResource,
       public thunk::PPB_BrowserFont_Singleton_API {
  public:
   BrowserFontSingletonResource(Connection connection, PP_Instance instance);
-  virtual ~BrowserFontSingletonResource();
+  ~BrowserFontSingletonResource() override;
 
   // Resource override.
-  virtual thunk::PPB_BrowserFont_Singleton_API*
+  thunk::PPB_BrowserFont_Singleton_API*
       AsPPB_BrowserFont_Singleton_API() override;
 
   // thunk::PPB_BrowserFontSingleton_API implementation.
-  virtual PP_Var GetFontFamilies(PP_Instance instance) override;
+  PP_Var GetFontFamilies(PP_Instance instance) override;
 
  private:
   // Lazily-filled-in list of font families.
   std::string families_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserFontSingletonResource);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_BROWSER_FONT_SINGLETON_RESOURCE_H_