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

content/browser/devtools/devtools_system_info_handler.h

 // Copyright 2013 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 CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_SYSTEM_INFO_HANDLER_H_
 #define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_SYSTEM_INFO_HANDLER_H_
 
 #include "content/browser/devtools/devtools_protocol.h"
 
 namespace content {
 
 // This class provides information to DevTools about the system it's running on.
 class DevToolsSystemInfoHandler
     : public DevToolsProtocol::Handler {
  public:
   DevToolsSystemInfoHandler();
-  virtual ~DevToolsSystemInfoHandler();
+  ~DevToolsSystemInfoHandler() override;
 
  private:
   scoped_refptr<DevToolsProtocol::Response> OnGetInfo(
       scoped_refptr<DevToolsProtocol::Command> command);
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsSystemInfoHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_SYSTEM_INFO_HANDLER_H_