Make using WebContentsUserData simpler.

chrome/browser/omnibox_search_hint.h

 // 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.
 
 #ifndef CHROME_BROWSER_OMNIBOX_SEARCH_HINT_H_
 #define CHROME_BROWSER_OMNIBOX_SEARCH_HINT_H_
 
 #include <map>
 #include <string>
 
@@ skipping 29 matching lines @@
 
   // Disables the hint infobar permanently, so that it does not show ever again.
   void DisableHint();
 
   // Returns true if the profile and current environment make the showing of the
   // hint infobar possible.
   static bool IsEnabled(Profile* profile);
 
  private:
   explicit OmniboxSearchHint(content::WebContents* web_contents);
-  static int kUserDataKey;
   friend class WebContentsUserData<OmniboxSearchHint>;
 
   void ShowInfoBar();
 
   content::NotificationRegistrar notification_registrar_;
 
   // The contents we are associated with.
   content::WebContents* web_contents_;
 
   // A map containing the URLs of the search engine for which we want to
   // trigger the hint.
   std::map<std::string, int> search_engine_urls_;
 
   DISALLOW_COPY_AND_ASSIGN(OmniboxSearchHint);
 };
 
 #endif  // CHROME_BROWSER_OMNIBOX_SEARCH_HINT_H_