Make using WebContentsUserData simpler.

chrome/browser/extensions/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_EXTENSIONS_TAB_HELPER_H_
 #define CHROME_BROWSER_EXTENSIONS_TAB_HELPER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
@@ skipping 127 matching lines @@
   ActiveTabPermissionGranter* active_tab_permission_granter() {
     return active_tab_permission_granter_.get();
   }
 
   // Sets a non-extension app icon associated with WebContents and fires an
   // INVALIDATE_TYPE_TITLE navigation state change to trigger repaint of title.
   void SetAppIcon(const SkBitmap& app_icon);
 
  private:
   explicit TabHelper(content::WebContents* web_contents);
-  static int kUserDataKey;
   friend class WebContentsUserData<TabHelper>;
 
   // content::WebContentsObserver overrides.
   virtual void RenderViewCreated(
       content::RenderViewHost* render_view_host) OVERRIDE;
   virtual void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void DidCloneToNewWebContents(
@@ skipping 95 matching lines @@
   scoped_ptr<LocationBarController> location_bar_controller_;
 
   scoped_ptr<ActiveTabPermissionGranter> active_tab_permission_granter_;
 
   DISALLOW_COPY_AND_ASSIGN(TabHelper);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_TAB_HELPER_H_