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

chrome/browser/pref_service_flags_storage.h

Index: chrome/browser/pref_service_flags_storage.h
diff --git a/chrome/browser/pref_service_flags_storage.h b/chrome/browser/pref_service_flags_storage.h
index 06dfaefc8631c9159ea6d7b3f5911f641c379292..ac41448e130a855dd9d31dafdc75ee96444e5b58 100644
--- a/chrome/browser/pref_service_flags_storage.h
+++ b/chrome/browser/pref_service_flags_storage.h
@@ -17,10 +17,10 @@ namespace about_flags {
 class PrefServiceFlagsStorage : public FlagsStorage {
  public:
   explicit PrefServiceFlagsStorage(PrefService *prefs);
-  virtual ~PrefServiceFlagsStorage();
+  ~PrefServiceFlagsStorage() override;
 
-  virtual std::set<std::string> GetFlags() override;
-  virtual bool SetFlags(const std::set<std::string>& flags) override;
+  std::set<std::string> GetFlags() override;
+  bool SetFlags(const std::set<std::string>& flags) override;
 
  private:
   PrefService* prefs_;