Various fixes for aria-activedescendant.

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

 /*
  * Copyright (C) 2012, 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 125 matching lines @@
 
     float value = valueForRange();
     float step = stepValueForRange();
 
     value += increase ? step : -step;
 
     setValue(String::number(value));
     axObjectCache().postNotification(getNode(), AXObjectCacheImpl::AXValueChanged);
 }
 
+AXObject* AXNodeObject::activeDescendant() const
+{
+    if (!getNode() || !getNode()->isElementNode())
+        return nullptr;
+
+    const AtomicString& activeDescendantAttr = getAttribute(aria_activedescendantAttr);
+    if (activeDescendantAttr.isNull() || activeDescendantAttr.isEmpty())
+        return nullptr;
+
+    Element* element = toElement(getNode());
+    Element* descendant = element->treeScope().getElementById(activeDescendantAttr);
+    if (!descendant)
+        return nullptr;
+
+    AXObject* axDescendant = axObjectCache().getOrCreate(descendant);
+    return axDescendant;
+}
+
 String AXNodeObject::ariaAccessibilityDescription() const
 {
     String ariaLabelledby = ariaLabelledbyAttribute();
     if (!ariaLabelledby.isEmpty())
         return ariaLabelledby;
 
     const AtomicString& ariaLabel = getAttribute(aria_labelAttr);
     if (!ariaLabel.isEmpty())
         return ariaLabel;
 
@@ skipping 902 matching lines @@
         return toHTMLFormControlElement(n)->isRequired();
 
     if (equalIgnoringCase(getAttribute(aria_requiredAttr), "true"))
         return true;
 
     return false;
 }
 
 bool AXNodeObject::canSetFocusAttribute() const
 {
-    Node* node = this->getNode();
+    Node* node = getNode();
     if (!node)
         return false;
 
     if (isWebArea())
         return true;
 
+    // Children of elements with an aria-activedescendant attribute should be
+    // focusable if they have an ARIA role.
+    if (ariaRoleAttribute() != UnknownRole && ancestorExposesActiveDescendant())
+        return true;
+
     // NOTE: It would be more accurate to ask the document whether setFocusedNode() would
     // do anything. For example, setFocusedNode() will do nothing if the current focused
     // node will not relinquish the focus.
-    if (!node)
-        return false;
-
     if (isDisabledFormControl(node))
         return false;
 
     return node->isElementNode() && toElement(node)->supportsFocus();
 }
 
 bool AXNodeObject::canSetValueAttribute() const
 {
     if (equalIgnoringCase(getAttribute(aria_readonlyAttr), "true"))
         return false;
 
     if (isProgressIndicator() || isSlider())
         return true;
 
     if (isTextControl() && !isNativeTextControl())
         return true;
 
     // Any node could be contenteditable, so isReadOnly should be relied upon
     // for this information for all elements.
     return !isReadOnly();
 }
 
+bool AXNodeObject::canSetSelectedAttribute() const
+{
+    // ARIA list box options can be selected if they are children of an element
+    // with an aria-activedescendant attribute.
+    if (ariaRoleAttribute() == ListBoxOptionRole && ancestorExposesActiveDescendant())
+        return true;
+    return AXObject::canSetSelectedAttribute();
+}
+
 bool AXNodeObject::canvasHasFallbackContent() const
 {
     Node* node = this->getNode();
     if (!isHTMLCanvasElement(node))
         return false;
 
     // If it has any children that are elements, we'll assume it might be fallback
     // content. If it has no children or its only children are not elements
     // (e.g. just text nodes), it doesn't have fallback content.
     return ElementTraversal::firstChild(*node);
@@ skipping 1646 matching lines @@
     return placeholder;
 }
 
 DEFINE_TRACE(AXNodeObject)
 {
     visitor->trace(m_node);
     AXObject::trace(visitor);
 }
 
 } // namespace blink