Make using WebContentsUserData simpler.

chrome/browser/extensions/tab_helper.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 "chrome/browser/extensions/tab_helper.h"
 
 #include "chrome/browser/extensions/activity_log.h"
 #include "chrome/browser/extensions/app_notify_channel_ui.h"
 #include "chrome/browser/extensions/crx_installer.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ skipping 27 matching lines @@
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_view.h"
 #include "ui/gfx/image/image.h"
 
 using content::NavigationController;
 using content::NavigationEntry;
 using content::RenderViewHost;
 using content::WebContents;
 
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(extensions::TabHelper)
+
 namespace {
 
 const char kPermissionError[] = "permission_error";
 
 }  // namespace
 
 namespace extensions {
 
-int TabHelper::kUserDataKey;
-
 TabHelper::ContentScriptObserver::ContentScriptObserver(TabHelper* tab_helper)
     : tab_helper_(tab_helper) {
   tab_helper_->AddContentScriptObserver(this);
 }
 
 TabHelper::ContentScriptObserver::ContentScriptObserver() : tab_helper_(NULL) {
 }
 
 TabHelper::ContentScriptObserver::~ContentScriptObserver() {
   if (tab_helper_)
@@ skipping 418 matching lines @@
     // malware site etc). When this happens, we abort the shortcut update.
     NavigationEntry* entry = controller.GetLastCommittedEntry();
     if (entry)
       GetApplicationInfo(entry->GetPageID());
     else
       pending_web_app_action_ = NONE;
   }
 }
 
 }  // namespace extensions