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

chrome/browser/autocomplete/shortcuts_backend.h

Index: chrome/browser/autocomplete/shortcuts_backend.h
diff --git a/chrome/browser/autocomplete/shortcuts_backend.h b/chrome/browser/autocomplete/shortcuts_backend.h
index d8ed072895b01549c5b172f84d0793887564f041..88d82ddbd92243edf0b0bc1f565ae9e5711c23fa 100644
--- a/chrome/browser/autocomplete/shortcuts_backend.h
+++ b/chrome/browser/autocomplete/shortcuts_backend.h
@@ -91,18 +91,18 @@ class ShortcutsBackend : public RefcountedKeyedService,
 
   typedef std::map<std::string, ShortcutMap::iterator> GuidMap;
 
-  virtual ~ShortcutsBackend();
+  ~ShortcutsBackend() override;
 
   static history::ShortcutsDatabase::Shortcut::MatchCore MatchToMatchCore(
       const AutocompleteMatch& match, Profile* profile);
 
   // RefcountedKeyedService:
-  virtual void ShutdownOnUIThread() override;
+  void ShutdownOnUIThread() override;
 
   // content::NotificationObserver:
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) override;
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
 
   // Internal initialization of the back-end. Posted by Init() to the DB thread.
   // On completion posts InitCompleted() back to UI thread.