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

chrome/browser/browsing_data/mock_browsing_data_service_worker_helper.h

Index: chrome/browser/browsing_data/mock_browsing_data_service_worker_helper.h
diff --git a/chrome/browser/browsing_data/mock_browsing_data_service_worker_helper.h b/chrome/browser/browsing_data/mock_browsing_data_service_worker_helper.h
index e3575f3538432bf39e59fd30eff9df8e62afcb48..00b18cba0bc7b81212f482463c978b5801166d74 100644
--- a/chrome/browser/browsing_data/mock_browsing_data_service_worker_helper.h
+++ b/chrome/browser/browsing_data/mock_browsing_data_service_worker_helper.h
@@ -36,12 +36,12 @@ class MockBrowsingDataServiceWorkerHelper
   bool AllDeleted();
 
   // BrowsingDataServiceWorkerHelper.
-  virtual void StartFetching(const base::Callback<void(
+  void StartFetching(const base::Callback<void(
       const std::list<content::ServiceWorkerUsageInfo>&)>& callback) override;
-  virtual void DeleteServiceWorkers(const GURL& origin) override;
+  void DeleteServiceWorkers(const GURL& origin) override;
 
  private:
-  virtual ~MockBrowsingDataServiceWorkerHelper();
+  ~MockBrowsingDataServiceWorkerHelper() override;
 
   base::Callback<void(const std::list<content::ServiceWorkerUsageInfo>&)>
       callback_;