Switch Extensions::TabHelper to use WebContents, WebContentsUserData.

BUG=107201
TEST=no visible change
[email protected]

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=155743

Reverted: http://src.chromium.org/viewvc/chrome?view=rev&revision=155901

Review URL: https://chromiumcodereview.appspot.com/10917026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@156366 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 8564c3a..facdd33 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1036,6 +1036,9 @@
                                          GetSiteInstance(), MSG_ROUTING_NONE,
                                          this, opener_);
   tc->GetController().CopyStateFrom(controller_);
+  FOR_EACH_OBSERVER(WebContentsObserver,
+                    observers_,
+                    DidCloneToNewWebContents(this, tc));
   return tc;
 }