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

chrome/browser/gpu/gl_string_manager.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_GPU_GL_STRING_MANAGER_H_
 #define CHROME_BROWSER_GPU_GL_STRING_MANAGER_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "content/public/browser/gpu_data_manager_observer.h"
 
 class PrefRegistrySimple;
 
 class GLStringManager : public content::GpuDataManagerObserver {
  public:
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
   GLStringManager();
-  virtual ~GLStringManager();
+  ~GLStringManager() override;
 
   // Get cached GL strings in local state and send them to GpuDataManager.
   void Initialize();
 
   // content::GpuDataManagerObserver
-  virtual void OnGpuInfoUpdate() override;
+  void OnGpuInfoUpdate() override;
 
  private:
   std::string gl_vendor_;
   std::string gl_renderer_;
   std::string gl_version_;
 
   DISALLOW_COPY_AND_ASSIGN(GLStringManager);
 };
 
 #endif  // CHROME_BROWSER_GPU_GL_STRING_MANAGER_H_