Switch Extensions::TabHelper to use WebContents, WebContentsUserData.

chrome/browser/ui/extensions/application_launch.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/extensions/application_launch.h"
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "chrome/browser/extensions/default_apps_trial.h"
@@ skipping 264 matching lines @@
   WebContents* tab = OpenApplicationWindow(
       profile,
       NULL,  // this is a URL app.  No extension.
       extension_misc::LAUNCH_WINDOW,
       url,
       &app_browser);
 
   if (!tab)
     return NULL;
 
-  TabContents* tab_contents = TabContents::FromWebContents(tab);
   // Set UPDATE_SHORTCUT as the pending web app action. This action is picked
   // up in LoadingStateChanged to schedule a GetApplicationInfo. And when
   // the web app info is available, extensions::TabHelper notifies Browser via
   // OnDidGetApplicationInfo, which calls
   // web_app::UpdateShortcutForTabContents when it sees UPDATE_SHORTCUT as
   // pending web app action.
-  tab_contents->extension_tab_helper()->set_pending_web_app_action(
+  extensions::TabHelper::FromWebContents(tab)->set_pending_web_app_action(
       extensions::TabHelper::UPDATE_SHORTCUT);
 
   return tab;
 }
 
 }  // namespace application_launch