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

chrome/browser/chrome_browser_main_mac.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 CHROME_BROWSER_CHROME_BROWSER_MAIN_MAC_H_
 #define CHROME_BROWSER_CHROME_BROWSER_MAIN_MAC_H_
 
 #include "chrome/browser/chrome_browser_main_posix.h"
 
 class ChromeBrowserMainPartsMac : public ChromeBrowserMainPartsPosix {
  public:
   explicit ChromeBrowserMainPartsMac(
       const content::MainFunctionParams& parameters);
-  virtual ~ChromeBrowserMainPartsMac();
+  ~ChromeBrowserMainPartsMac() override;
 
   // BrowserParts overrides.
-  virtual void PreEarlyInitialization() override;
-  virtual void PreMainMessageLoopStart() override;
-  virtual void PostMainMessageLoopStart() override;
-  virtual void PreProfileInit() override;
-  virtual void PostProfileInit() override;
+  void PreEarlyInitialization() override;
+  void PreMainMessageLoopStart() override;
+  void PostMainMessageLoopStart() override;
+  void PreProfileInit() override;
+  void PostProfileInit() override;
 
   // Perform platform-specific work that needs to be done after the main event
   // loop has ended. The embedder must be sure to call this.
   static void DidEndMainMessageLoop();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainPartsMac);
 };
 
 #endif  // CHROME_BROWSER_CHROME_BROWSER_MAIN_MAC_H_