One AXObjectCache per frame

Source/web/ChromeClientImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 193 matching lines @@
     if (toNode && toNode->isElementNode() && toElement(toNode)->isLiveLink() && toNode->shouldHaveFocusAppearance())
         focusURL = toElement(toNode)->hrefURL();
     m_webView->client()->setKeyboardFocusURL(focusURL);
 }
 
 void ChromeClientImpl::focusedFrameChanged(LocalFrame* frame)
 {
     WebLocalFrameImpl* webframe = WebLocalFrameImpl::fromFrame(frame);
     if (webframe && webframe->client())
         webframe->client()->frameFocused();
+
+    m_webView->client()->focusedFrameChanged();

[dcheng, 2015/09/17 21:54:08]

How come we can't just piggyback off the WebFrameClient notification?

Also, is it possible for WebViewClient to ever be null here?

[dmazzoni, 2015/09/17 22:11:57]

That goes to only the frame that got focus.

To avoid ambiguity and race conditions, I've decided to let the main frame send
the accessible notification that the focused frame has changed.

When the frame that gets focus isn't local, |frame| will be null but this
function still gets called. In that case the WebFrameClient notification won't
get called because it's not local.
Not that I'm aware of. Other uses of m_webView->client() don't do any null
checks.

 }
 
 namespace {
 
 void updatePolicyForEvent(const WebInputEvent* inputEvent, NavigationPolicy* policy)
 {
     if (!inputEvent)
         return;
 
     unsigned short buttonNumber = 0;
@@ skipping 771 matching lines @@
     for (const auto& observer : observers)
         observer->willOpenPopup();
 }
 
 FloatSize ChromeClientImpl::elasticOverscroll() const
 {
     return m_webView->elasticOverscroll();
 }
 
 } // namespace blink