Standardize usage of virtual/override/final in extensions/

extensions/browser/view_type_utils.cc

 // Copyright (c) 2012 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 "extensions/browser/view_type_utils.h"
 
 #include "base/lazy_instance.h"
 #include "content/public/browser/web_contents.h"
 
 using content::WebContents;
 
 namespace extensions {
 
 namespace {
 
 const char kViewTypeUserDataKey[] = "ViewTypeUserData";
 
 class ViewTypeUserData : public base::SupportsUserData::Data {
  public:
   explicit ViewTypeUserData(ViewType type) : type_(type) {}
-  virtual ~ViewTypeUserData() {}
+  ~ViewTypeUserData() override {}
   ViewType type() { return type_; }
 
  private:
   ViewType type_;
 };
 
 }  // namespace
 
 ViewType GetViewType(WebContents* tab) {
   if (!tab)
     return VIEW_TYPE_INVALID;
 
   ViewTypeUserData* user_data = static_cast<ViewTypeUserData*>(
       tab->GetUserData(&kViewTypeUserDataKey));
 
   return user_data ? user_data->type() : VIEW_TYPE_INVALID;
 }
 
 void SetViewType(WebContents* tab, ViewType type) {
   tab->SetUserData(&kViewTypeUserDataKey, new ViewTypeUserData(type));
 }
 
 }  // namespace extensions