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

ppapi/proxy/broker_dispatcher.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_BROKER_DISPATCHER_H_
 #define PPAPI_PROXY_BROKER_DISPATCHER_H_
 
 #include "base/compiler_specific.h"
 #include "ppapi/c/trusted/ppp_broker.h"
 #include "ppapi/proxy/proxy_channel.h"
 
 namespace ppapi {
 namespace proxy {
 
 class PPAPI_PROXY_EXPORT BrokerDispatcher : public ProxyChannel {
  public:
-  virtual ~BrokerDispatcher();
+  ~BrokerDispatcher() override;
 
   // You must call this function before anything else. Returns true on success.
   // The delegate pointer must outlive this class, ownership is not
   // transferred.
   virtual bool InitBrokerWithChannel(ProxyChannel::Delegate* delegate,
                                      base::ProcessId peer_pid,
                                      const IPC::ChannelHandle& channel_handle,
                                      bool is_client);
 
   // IPC::Listener implementation.
-  virtual bool OnMessageReceived(const IPC::Message& msg) override;
+  bool OnMessageReceived(const IPC::Message& msg) override;
 
  protected:
   // You must call InitBrokerWithChannel after the constructor.
   explicit BrokerDispatcher(PP_ConnectInstance_Func connect_instance);
 
   void OnMsgConnectToPlugin(PP_Instance instance,
                             IPC::PlatformFileForTransit handle,
                             int32_t* result);
 
   PP_ConnectInstance_Func connect_instance_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BrokerDispatcher);
 };
 
 // The dispatcher for the browser side of the broker channel.
 class PPAPI_PROXY_EXPORT BrokerHostDispatcher : public BrokerDispatcher {
  public:
   BrokerHostDispatcher();
 
   // IPC::Listener implementation.
-  virtual void OnChannelError() override;
+  void OnChannelError() override;
 };
 
 // The dispatcher for the broker side of the broker channel.
 class PPAPI_PROXY_EXPORT BrokerSideDispatcher : public BrokerDispatcher {
  public:
   explicit BrokerSideDispatcher(PP_ConnectInstance_Func connect_instance);
 
   // IPC::Listener implementation.
-  virtual void OnChannelError() override;
+  void OnChannelError() override;
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_BROKER_DISPATCHER_H_