Make using WebContentsUserData simpler.

chrome/browser/ui/pdf/pdf_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/pdf/pdf_tab_helper.h"
 
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/omnibox/location_bar.h"
 #include "chrome/browser/ui/pdf/open_pdf_in_reader_prompt_delegate.h"
 #include "chrome/browser/ui/pdf/pdf_unsupported_feature.h"
 #include "chrome/common/render_messages.h"
 #include "content/public/browser/navigation_details.h"
 
-int PDFTabHelper::kUserDataKey;
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(PDFTabHelper)
 
 PDFTabHelper::PDFTabHelper(content::WebContents* web_contents)
     : content::WebContentsObserver(web_contents) {
 }
 
 PDFTabHelper::~PDFTabHelper() {
 }
 
 void PDFTabHelper::ShowOpenInReaderPrompt(
     scoped_ptr<OpenPDFInReaderPromptDelegate> prompt) {
@@ skipping 33 matching lines @@
   LocationBar* location_bar = window->GetLocationBar();
   if (!location_bar)
     return;
 
   location_bar->UpdateOpenPDFInReaderPrompt();
 }
 
 void PDFTabHelper::OnPDFHasUnsupportedFeature() {
   PDFHasUnsupportedFeature(web_contents());
 }