Standardize usage of virtual/override/final in extensions/

extensions/browser/image_loader_factory.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 EXTENSIONS_BROWSER_IMAGE_LOADER_FACTORY_H_
 #define EXTENSIONS_BROWSER_IMAGE_LOADER_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
@@ skipping 12 matching lines @@
 class ImageLoaderFactory : public BrowserContextKeyedServiceFactory {
  public:
   static ImageLoader* GetForBrowserContext(content::BrowserContext* context);
 
   static ImageLoaderFactory* GetInstance();
 
  private:
   friend struct DefaultSingletonTraits<ImageLoaderFactory>;
 
   ImageLoaderFactory();
-  virtual ~ImageLoaderFactory();
+  ~ImageLoaderFactory() override;
 
   // BrowserContextKeyedServiceFactory:
-  virtual KeyedService* BuildServiceInstanceFor(
+  KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
-  virtual bool ServiceIsCreatedWithBrowserContext() const override;
-  virtual content::BrowserContext* GetBrowserContextToUse(
+  bool ServiceIsCreatedWithBrowserContext() const override;
+  content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_IMAGE_LOADER_FACTORY_H_