Mouse event handlers use user gesture tokens on top-level LocalFrames.

Source/core/frame/LocalFrame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 598 matching lines @@
 
 void LocalFrame::disconnectOwnerElement()
 {
     if (ownerElement()) {
         if (Document* doc = document())
             doc->topDocument().clearAXObjectCache();
     }
     Frame::disconnectOwnerElement();
 }
 
+LocalFrame* LocalFrame::localFrameRoot()
+{
+    LocalFrame* curFrame = this;
+    while (curFrame && curFrame->tree().parent() && curFrame->tree().parent()->isLocalFrame())
+        curFrame = curFrame->tree().parent();
+
+    return curFrame;
+}
+
 } // namespace WebCore