Make using WebContentsUserData simpler.

chrome/browser/ssl/ssl_tab_helper.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_SSL_SSL_TAB_HELPER_H_
 #define CHROME_BROWSER_SSL_SSL_TAB_HELPER_H_
 
 #include <map>
 
 #include "base/callback_forward.h"
@@ skipping 41 matching lines @@
 
   // Displays a dialog for selecting a client certificate and returns it to
   // the |handler|.
   void ShowClientCertificateRequestDialog(
       const net::HttpNetworkSession* network_session,
       net::SSLCertRequestInfo* cert_request_info,
       const base::Callback<void(net::X509Certificate*)>& callback);
 
  private:
   explicit SSLTabHelper(content::WebContents* contents);
-  static int kUserDataKey;
   friend class WebContentsUserData<SSLTabHelper>;
 
   content::WebContents* web_contents_;
 
   class SSLAddCertData;
   std::map<int, linked_ptr<SSLAddCertData> > request_id_to_add_cert_data_;
 
   SSLAddCertData* GetAddCertData(SSLAddCertHandler* handler);
 
   DISALLOW_COPY_AND_ASSIGN(SSLTabHelper);
 };
 
 #endif  // CHROME_BROWSER_SSL_SSL_TAB_HELPER_H_