Make the WebContentsUserData locator key private.

chrome/browser/infobars/infobar_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/infobars/infobar_tab_helper.h"
 
 #include "chrome/browser/api/infobars/infobar_delegate.h"
 #include "chrome/browser/infobars/infobar.h"
 #include "chrome/browser/infobars/insecure_content_infobar_delegate.h"
 #include "chrome/common/chrome_notification_types.h"
@@ skipping 201 matching lines @@
     }
 
     return;
   }
 
   DCHECK_EQ(type, content::NOTIFICATION_WEB_CONTENTS_DESTROYED);
   // The WebContents is going away; be aggressively paranoid and delete
   // ourselves lest other parts of the system attempt to add infobars or use
   // us otherwise during the destruction.
   DCHECK_EQ(web_contents(), content::Source<WebContents>(source).ptr());
-  web_contents()->RemoveUserData(&kLocatorKey);
+  web_contents()->RemoveUserData(UserDataKey());
   // That was the equivalent of "delete this". This object is now destroyed;
   // returning from this function is the only safe thing to do.
   return;
 }