One accessibility tree per frame.

third_party/WebKit/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 370 matching lines @@
     String message = "Unsafe JavaScript attempt to initiate navigation for frame " + targetFrameDescription + " from frame with URL '" + document()->url().getString() + "'. " + reason + "\n";
 
     localDOMWindow()->printErrorMessage(message);
 }
 
 WindowProxyManager* LocalFrame::windowProxyManager() const
 {
     return m_script->windowProxyManager();
 }
 
-void LocalFrame::disconnectOwnerElement()
-{
-    if (owner()) {
-        if (Document* document = this->document())
-            document->topDocument().clearAXObjectCache();
-    }
-    Frame::disconnectOwnerElement();
-}
-
 bool LocalFrame::shouldClose()
 {
     // TODO(dcheng): This should be fixed to dispatch beforeunload events to
     // both local and remote frames.
     return m_loader.shouldClose();
 }
 
 void LocalFrame::willDetachFrameHost()
 {
     LocalFrameLifecycleNotifier::notifyWillDetachFrameHost();
@@ skipping 465 matching lines @@
 {
     m_frame->disableNavigation();
 }
 
 FrameNavigationDisabler::~FrameNavigationDisabler()
 {
     m_frame->enableNavigation();
 }
 
 } // namespace blink