Switch Extensions::TabHelper to use WebContents, WebContentsUserData.

chrome/browser/extensions/active_tab_unittest.cc

Index: chrome/browser/extensions/active_tab_unittest.cc
diff --git a/chrome/browser/extensions/active_tab_unittest.cc b/chrome/browser/extensions/active_tab_unittest.cc
index ea3b5cd07e3c23ecafb3f6eeb01ecb83f074045a..cbbc43873857f76a10eff440725ac08a66d21163 100644
--- a/chrome/browser/extensions/active_tab_unittest.cc
+++ b/chrome/browser/extensions/active_tab_unittest.cc
@@ -67,8 +67,8 @@ class ActiveTabTest : public TabContentsTestHarness {
   }
 
   ActiveTabPermissionManager* active_tab_permission_manager() {
-    return tab_contents()->extension_tab_helper()->
-                           active_tab_permission_manager();
+    return extensions::TabHelper::FromWebContents(web_contents())->
+        active_tab_permission_manager();
   }
 
   bool IsAllowed(const scoped_refptr<const Extension>& extension,