Standardize usage of virtual/override/final in chrome/browser/task_manager/

chrome/browser/task_manager/background_information.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 CHROME_BROWSER_TASK_MANAGER_BACKGROUND_INFORMATION_H_
 #define CHROME_BROWSER_TASK_MANAGER_BACKGROUND_INFORMATION_H_
 
 #include "base/basictypes.h"
 #include "chrome/browser/task_manager/web_contents_information.h"
 
 namespace task_manager {
 
 // WebContentsInformation for BackgroundContents-owned WebContentses.
 class BackgroundInformation
     : public NotificationObservingWebContentsInformation {
  public:
   BackgroundInformation();
-  virtual ~BackgroundInformation();
+  ~BackgroundInformation() override;
 
   // WebContentsInformation implementation.
-  virtual bool CheckOwnership(content::WebContents* web_contents) override;
-  virtual void GetAll(const NewWebContentsCallback& callback) override;
-  virtual scoped_ptr<RendererResource> MakeResource(
+  bool CheckOwnership(content::WebContents* web_contents) override;
+  void GetAll(const NewWebContentsCallback& callback) override;
+  scoped_ptr<RendererResource> MakeResource(
       content::WebContents* web_contents) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BackgroundInformation);
 };
 
 }  // namespace task_manager
 
 #endif  // CHROME_BROWSER_TASK_MANAGER_BACKGROUND_INFORMATION_H_