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

chrome/browser/extensions/api/tabs/tabs_windows_api.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_EXTENSIONS_API_TABS_TABS_WINDOWS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_TABS_TABS_WINDOWS_API_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/event_router.h"
 
 namespace extensions {
 class TabsEventRouter;
 class WindowsEventRouter;
 
 class TabsWindowsAPI : public BrowserContextKeyedAPI,
                        public EventRouter::Observer {
  public:
   explicit TabsWindowsAPI(content::BrowserContext* context);
-  virtual ~TabsWindowsAPI();
+  ~TabsWindowsAPI() override;
 
   // Convenience method to get the TabsWindowsAPI for a profile.
   static TabsWindowsAPI* Get(content::BrowserContext* context);
 
   TabsEventRouter* tabs_event_router();
   WindowsEventRouter* windows_event_router();
 
   // KeyedService implementation.
-  virtual void Shutdown() override;
+  void Shutdown() override;
 
   // BrowserContextKeyedAPI implementation.
   static BrowserContextKeyedAPIFactory<TabsWindowsAPI>* GetFactoryInstance();
 
   // EventRouter::Observer implementation.
-  virtual void OnListenerAdded(const extensions::EventListenerInfo& details)
-      override;
+  void OnListenerAdded(const extensions::EventListenerInfo& details) override;
 
  private:
   friend class BrowserContextKeyedAPIFactory<TabsWindowsAPI>;
 
   content::BrowserContext* browser_context_;
 
   // BrowserContextKeyedAPI implementation.
   static const char* service_name() {
     return "TabsWindowsAPI";
   }
   static const bool kServiceIsNULLWhileTesting = true;
 
   scoped_ptr<TabsEventRouter> tabs_event_router_;
   scoped_ptr<WindowsEventRouter> windows_event_router_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_TABS_TABS_WINDOWS_API_H_