Standardize usage of virtual/override/final in chrome/browser/supervised_user/

chrome/browser/supervised_user/supervised_user_interstitial.cc

 // 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.
 
 #include "chrome/browser/supervised_user/supervised_user_interstitial.h"
 
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 47 matching lines @@
  private:
   friend class content::WebContentsUserData<TabCloser>;
 
   explicit TabCloser(WebContents* web_contents)
       : web_contents_(web_contents), weak_ptr_factory_(this) {
     BrowserThread::PostTask(
         BrowserThread::UI,
         FROM_HERE,
         base::Bind(&TabCloser::CloseTabImpl, weak_ptr_factory_.GetWeakPtr()));
   }
-  virtual ~TabCloser() {}
+  ~TabCloser() override {}
 
   void CloseTabImpl() {
     // On Android, FindBrowserWithWebContents and TabStripModel don't exist.
 #if !defined(OS_ANDROID)
     Browser* browser = chrome::FindBrowserWithWebContents(web_contents_);
     DCHECK(browser);
     TabStripModel* tab_strip = browser->tab_strip_model();
     DCHECK_NE(TabStripModel::kNoTab,
               tab_strip->GetIndexOfWebContents(web_contents_));
     if (tab_strip->count() <= 1) {
@@ skipping 220 matching lines @@
       SupervisedUserServiceFactory::GetForProfile(profile_);
   supervised_user_service->RemoveObserver(this);
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE, base::Bind(callback_, continue_request));
 
   // After this, the WebContents may be destroyed. Make sure we don't try to use
   // it again.
   web_contents_ = NULL;
 }