Update {virtual,override} to follow C++11 style in cloud_print.

cloud_print/gcp20/prototype/cloud_print_request.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 CLOUD_PRINT_GCP20_PROTOTYPE_CLOUD_PRINT_REQUEST_H_
 #define CLOUD_PRINT_GCP20_PROTOTYPE_CLOUD_PRINT_REQUEST_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 20 matching lines @@
     // Use for erasing instance of CloudPrintRequest class.
     virtual void OnFetchError(const std::string& server_api,
                               int server_code,
                               int server_http_code) = 0;
 
     // Invoked when timeout is reached.
     // Use for erasing instance of CloudPrintRequest class.
     virtual void OnFetchTimeoutReached() = 0;
   };
 
-  virtual ~CloudPrintRequest();
+  ~CloudPrintRequest() override;
 
   // Creates GET request.
   static scoped_ptr<CloudPrintRequest> CreateGet(const GURL& url,
                                                  Delegate* delegate);
 
   // Creates POST request.
   static scoped_ptr<CloudPrintRequest> CreatePost(const GURL& url,
                                                   const std::string& content,
                                                   const std::string& mimetype,
                                                   Delegate* delegate);
 
   // Starts request. Once fetch was completed, parser will be called.
   void Run(const std::string& access_token,
            scoped_refptr<net::URLRequestContextGetter> context_getter);
 
   // Add header to request.
   void AddHeader(const std::string& header);
 
  private:
   CloudPrintRequest(const GURL& url,
                     net::URLFetcher::RequestType method,
                     Delegate* delegate);
 
   // net::URLFetcherDelegate methods:
-  virtual void OnURLFetchComplete(const net::URLFetcher* source) override;
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
 
   // Method for handling timeout.
   void OnRequestTimeout();
 
   scoped_ptr<net::URLFetcher> fetcher_;
 
   Delegate* delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(CloudPrintRequest);
 };
 
 #endif  // CLOUD_PRINT_GCP20_PROTOTYPE_CLOUD_PRINT_REQUEST_H_