Various fixes for aria-activedescendant.

third_party/WebKit/Source/modules/accessibility/AXObjectCacheImpl.cpp

 /*
  * Copyright (C) 2014, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 137 matching lines @@
         if (toAXImageMapLink(child)->areaElement() == areaElement)
             return child;
     }
 
     return 0;
 }
 
 AXObject* AXObjectCacheImpl::focusedObject()
 {
     if (!accessibilityEnabled())
-        return 0;
+        return nullptr;
 
     Node* focusedNode = m_document->focusedElement();
     if (!focusedNode)
         focusedNode = m_document;
 
     // If it's an image map, get the focused link within the image map.
     if (isHTMLAreaElement(focusedNode))
         return focusedImageMapUIElement(toHTMLAreaElement(focusedNode));
 
     // See if there's a page popup, for example a calendar picker.
     Element* adjustedFocusedElement = m_document->adjustedFocusedElement();
     if (isHTMLInputElement(adjustedFocusedElement)) {
         if (AXObject* axPopup = toHTMLInputElement(adjustedFocusedElement)->popupRootAXObject()) {
             if (Element* focusedElementInPopup = axPopup->getDocument()->focusedElement())
                 focusedNode = focusedElementInPopup;
         }
-
     }
 
     AXObject* obj = getOrCreate(focusedNode);
     if (!obj)
-        return 0;
+        return nullptr;
 
-    if (obj->shouldFocusActiveDescendant()) {
+    if (obj->supportsActiveDescendant()) {

[dmazzoni, 2016/03/31 05:48:30]

Hmmm, this code makes it seem like we were already following the active
descendant when determining what node has focus. Why was this not working?

         if (AXObject* descendant = obj->activeDescendant())
             obj = descendant;
     }
 
     // the HTML element, for example, is focusable but has an AX object that is ignored
     if (obj->accessibilityIsIgnored())
         obj = obj->parentObjectUnignored();
 
     return obj;
 }
@@ skipping 1096 matching lines @@
     visitor->trace(m_nodeObjectMapping);
 #endif
 
     visitor->trace(m_objects);
     visitor->trace(m_notificationsToPost);
 
     AXObjectCache::trace(visitor);
 }
 
 } // namespace blink