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

chrome/browser/browsing_data/browsing_data_service_worker_helper.h

Index: chrome/browser/browsing_data/browsing_data_service_worker_helper.h
diff --git a/chrome/browser/browsing_data/browsing_data_service_worker_helper.h b/chrome/browser/browsing_data/browsing_data_service_worker_helper.h
index e4861e8cd8ece09cee82df7cf46cf36fcabfbeb5..100741fb1099d0c92b6709c5a3770323c6d3e20f 100644
--- a/chrome/browser/browsing_data/browsing_data_service_worker_helper.h
+++ b/chrome/browser/browsing_data/browsing_data_service_worker_helper.h
@@ -126,12 +126,12 @@ class CannedBrowsingDataServiceWorkerHelper
       GetServiceWorkerUsageInfo() const;
 
   // BrowsingDataServiceWorkerHelper methods.
-  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 ~CannedBrowsingDataServiceWorkerHelper();
+  ~CannedBrowsingDataServiceWorkerHelper() override;
 
   std::set<PendingServiceWorkerUsageInfo> pending_service_worker_info_;