Standardize usage of virtual/override/final in extensions/

extensions/browser/api/serial/serial_event_dispatcher.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 EXTENSIONS_BROWSER_API_SERIAL_SERIAL_EVENT_DISPATCHER_H_
 #define EXTENSIONS_BROWSER_API_SERIAL_SERIAL_EVENT_DISPATCHER_H_
 
 #include <string>
 
 #include "extensions/browser/api/api_resource_manager.h"
 #include "extensions/common/api/serial.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
 struct Event;
 class SerialConnection;
 
 namespace core_api {
 
 // Per-browser-context dispatcher for events on serial connections.
 class SerialEventDispatcher : public BrowserContextKeyedAPI {
  public:
   explicit SerialEventDispatcher(content::BrowserContext* context);
-  virtual ~SerialEventDispatcher();
+  ~SerialEventDispatcher() override;
 
   // Start receiving data and firing events for a connection.
   void PollConnection(const std::string& extension_id, int connection_id);
 
   static SerialEventDispatcher* Get(content::BrowserContext* context);
 
   // BrowserContextKeyedAPI implementation.
   static BrowserContextKeyedAPIFactory<SerialEventDispatcher>*
       GetFactoryInstance();
 
@@ skipping 33 matching lines @@
   content::BrowserThread::ID thread_id_;
   content::BrowserContext* const context_;
   scoped_refptr<ConnectionData> connections_;
 };
 
 }  // namespace core_api
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_SERIAL_SERIAL_EVENT_DISPATCHER_H_