Add OVERRIDE to base/.

base/test/signaling_task.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.
 
 // A simple callback that you can use to wait for events on a thread.
 
 #ifndef BASE_TEST_SIGNALING_TASK_H_
 #define BASE_TEST_SIGNALING_TASK_H_
 #pragma once
 
 #include "base/task.h"
 
 namespace base {
 
 class WaitableEvent;
 
 class SignalingTask : public Task {
  public:
   explicit SignalingTask(base::WaitableEvent* event);
   virtual ~SignalingTask();
 
-  virtual void Run();
+  virtual void Run() OVERRIDE;
 
  private:
   base::WaitableEvent* event_;
   DISALLOW_COPY_AND_ASSIGN(SignalingTask);
 };
 
 }  // namespace base
 
 #endif  // BASE_TEST_SIGNALING_TASK_H_