Make using WebContentsUserData simpler.

chrome/browser/ui/zoom/zoom_controller.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/ui/zoom/zoom_controller.h"
 
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/tab_contents/tab_contents.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/page_zoom.h"
 #include "grit/theme_resources.h"
 #include "net/base/net_util.h"
 
-int ZoomController::kUserDataKey;
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(ZoomController)
 
 ZoomController::ZoomController(content::WebContents* web_contents)
     : content::WebContentsObserver(web_contents),
       zoom_percent_(100),
       observer_(NULL) {
   Profile* profile =
       Profile::FromBrowserContext(web_contents->GetBrowserContext());
   default_zoom_level_.Init(prefs::kDefaultZoomLevel, profile->GetPrefs(), this);
 
   content::HostZoomMap* zoom_map =
@@ skipping 51 matching lines @@
       host != net::GetHostOrSpecFromURL(web_contents()->GetURL())) {
     return;
   }
 
   bool dummy;
   zoom_percent_ = web_contents()->GetZoomPercent(&dummy, &dummy);
 
   if (observer_)
     observer_->OnZoomChanged(web_contents(), !host.empty());
 }