Standardize usage of virtual/override/final in ipc/

ipc/ipc_test_channel_listener.h

 // Copyright 2014 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 IPC_IPC_TEST_CHANNEL_LISTENER_H_
 #define IPC_IPC_TEST_CHANNEL_LISTENER_H_
 
 #include "ipc/ipc_listener.h"
 
 namespace IPC {
 
 class Sender;
 
 // A generic listener that expects messages of a certain type (see
 // OnMessageReceived()), and either sends a generic response or quits after the
 // 50th message (or on channel error).
 class TestChannelListener : public Listener {
  public:
   static const size_t kLongMessageStringNumBytes = 50000;
   static void SendOneMessage(Sender* sender, const char* text);
 
   TestChannelListener() : sender_(NULL), messages_left_(50) {}
-  virtual ~TestChannelListener() {}
+  ~TestChannelListener() override {}
 
-  virtual bool OnMessageReceived(const Message& message) override;
-  virtual void OnChannelError() override;
+  bool OnMessageReceived(const Message& message) override;
+  void OnChannelError() override;
 
   void Init(Sender* s) {
     sender_ = s;
   }
 
   bool HasSentAll() const { return 0 == messages_left_; }
 
  protected:
   void SendNextMessage();
 
  private:
   Sender* sender_;
   int messages_left_;
 };
 
 }
 
 #endif // IPC_IPC_TEST_CHANNEL_LISTENER_H_