Standardize usage of virtual/override/final in base/

base/prefs/pref_member.h

 // Copyright (c) 2012 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.
 //
 // A helper class that stays in sync with a preference (bool, int, real,
 // string or filepath).  For example:
 //
 // class MyClass {
 //  public:
 //   MyClass(PrefService* prefs) {
@@ skipping 98 matching lines @@
 
   virtual void CreateInternal() const = 0;
 
   // See PrefMember<> for description.
   void Destroy();
 
   void MoveToThread(
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
 
   // PrefObserver
-  virtual void OnPreferenceChanged(PrefService* service,
-                                   const std::string& pref_name) override;
+  void OnPreferenceChanged(PrefService* service,
+                           const std::string& pref_name) override;
 
   void VerifyValuePrefName() const {
     DCHECK(!pref_name_.empty());
   }
 
   // This method is used to do the actual sync with the preference.
   // Note: it is logically const, because it doesn't modify the state
   // seen by the outside world. It is just doing a lazy load behind the scenes.
   void UpdateValueFromPref(const base::Closure& callback) const;
 
@@ skipping 214 matching lines @@
 
 typedef PrefMember<bool> BooleanPrefMember;
 typedef PrefMember<int> IntegerPrefMember;
 typedef PrefMember<double> DoublePrefMember;
 typedef PrefMember<std::string> StringPrefMember;
 typedef PrefMember<base::FilePath> FilePathPrefMember;
 // This preference member is expensive for large string arrays.
 typedef PrefMember<std::vector<std::string> > StringListPrefMember;
 
 #endif  // BASE_PREFS_PREF_MEMBER_H_