Standardize usage of virtual/override/final specifiers.

components/timers/alarm_timer.h

 // Copyright 2014 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.
 
 #ifndef COMPONENTS_TIMER_ALARM_TIMER_H_
 #define COMPONENTS_TIMER_ALARM_TIMER_H_
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ skipping 41 matching lines @@
     friend class base::RefCountedThreadSafe<Delegate>;
   };
 
   AlarmTimer(bool retain_user_task, bool is_repeating);
 
   AlarmTimer(const tracked_objects::Location& posted_from,
              base::TimeDelta delay,
              const base::Closure& user_task,
              bool is_repeating);
 
-  virtual ~AlarmTimer();
+  ~AlarmTimer() override;
 
   // Timer overrides.
   void Stop() override;
   void Reset() override;
 
   // MessageLoop::DestructionObserver overrides.
   void WillDestroyCurrentMessageLoop() override;
 
   // Must be called by the delegate to indicate that the timer has fired and
   // that the user task should be run.
@@ skipping 21 matching lines @@
   base::MessageLoop* origin_message_loop_;
 
   base::WeakPtrFactory<AlarmTimer> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AlarmTimer);
 };
 
 }  // namespace timers
 
 #endif  // COMPONENTS_TIMER_ALARM_TIMER_H_