Make using WebContentsUserData simpler.

chrome/browser/ui/tab_contents/core_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/ui/tab_contents/core_tab_helper.h"
 
 #include "chrome/browser/renderer_host/web_cache_manager.h"
 #include "chrome/browser/ui/tab_contents/tab_contents.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
 #include "net/base/load_states.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 
 using content::WebContents;
 
-int CoreTabHelper::kUserDataKey;
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(CoreTabHelper)
 
 CoreTabHelper::CoreTabHelper(WebContents* web_contents)
     : content::WebContentsObserver(web_contents),
       delegate_(NULL) {
 }
 
 CoreTabHelper::~CoreTabHelper() {
 }
 
 string16 CoreTabHelper::GetDefaultTitle() {
@@ skipping 49 matching lines @@
   return string16();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // WebContentsObserver overrides
 
 void CoreTabHelper::WasShown() {
   WebCacheManager::GetInstance()->ObserveActivity(
       web_contents()->GetRenderProcessHost()->GetID());
 }