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

ppapi/proxy/plugin_resource_var.h

 // Copyright 2013 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_PLUGIN_RESOURCE_VAR_H_
 #define PPAPI_PROXY_PLUGIN_RESOURCE_VAR_H_
 
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/proxy/ppapi_proxy_export.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/shared_impl/resource_var.h"
 #include "ppapi/shared_impl/var.h"
 
 // Represents a resource Var, usable on the plugin side.
 class PPAPI_PROXY_EXPORT PluginResourceVar : public ppapi::ResourceVar {
  public:
   // Makes a null resource var.
   PluginResourceVar();
 
   // Makes a resource var with an existing resource.
   // Takes one reference to the given resource.
   explicit PluginResourceVar(ppapi::Resource* resource);
 
   // ResourceVar override.
-  virtual PP_Resource GetPPResource() const override;
-  virtual bool IsPending() const override;
+  PP_Resource GetPPResource() const override;
+  bool IsPending() const override;
 
   scoped_refptr<ppapi::Resource> resource() const { return resource_; }
 
  protected:
-  virtual ~PluginResourceVar();
+  ~PluginResourceVar() override;
 
  private:
   // If NULL, this represents the PP_Resource 0.
   scoped_refptr<ppapi::Resource> resource_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginResourceVar);
 };
 
 #endif