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

ppapi/proxy/proxy_object_var.h

 // Copyright (c) 2011 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_PROXY_OBJECT_VAR_H_
 #define PPAPI_PROXY_PROXY_OBJECT_VAR_H_
 
 #include "base/compiler_specific.h"
 #include "ppapi/proxy/ppapi_proxy_export.h"
 #include "ppapi/shared_impl/var.h"
 
 namespace ppapi {
 
 namespace proxy {
 class PluginDispatcher;
 }  // namespace proxy
 
 // Tracks a reference to an object var in the plugin side of the proxy. This
 // just stores the dispatcher and host var ID, and provides the interface for
 // integrating this with PP_Var creation.
 class PPAPI_PROXY_EXPORT ProxyObjectVar : public Var {
  public:
   ProxyObjectVar(proxy::PluginDispatcher* dispatcher,
                  int32 host_var_id);
 
-  virtual ~ProxyObjectVar();
+  ~ProxyObjectVar() override;
 
   // Var overrides.
-  virtual ProxyObjectVar* AsProxyObjectVar() override;
-  virtual PP_VarType GetType() const override;
+  ProxyObjectVar* AsProxyObjectVar() override;
+  PP_VarType GetType() const override;
 
   proxy::PluginDispatcher* dispatcher() const { return dispatcher_; }
   int32 host_var_id() const { return host_var_id_; }
 
   void* user_data() const { return user_data_; }
   void set_user_data(void* ud) { user_data_ = ud; }
 
   // Expose AssignVarID on Var so the PluginResourceTracker can call us when
   // it's creating IDs.
   void AssignVarID(int32 id);
 
   void clear_dispatcher() { dispatcher_ = NULL; }
 
  private:
   proxy::PluginDispatcher* dispatcher_;
   int32 host_var_id_;
 
   // When this object is created as representing a var implemented by the
   // plugin, this stores the user data so that we can look it up later. See
   // PluginVarTracker.
   void* user_data_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyObjectVar);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PROXY_OBJECT_VAR_H_