Various fixes for aria-activedescendant.

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

 /*
  * Copyright (C) 2008, 2009, 2011 Apple 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 312 matching lines @@
     "scrollbar",
     "slider",
     "spinbutton",
     "status",
     "tab",
     "tabpanel",
     "textbox",
     "timer",
     "tooltip",
     "treeitem",
-    // Composite user interface widgets.  This list is also from w3.org site refrerenced above.
+    // Composite user interface widgets.
+    // This list is also from the w3.org site referenced above.
     "combobox",
     "grid",
     "listbox",
     "menu",
     "menubar",
     "radiogroup",
     "tablist",
     "tree",
     "treegrid"
 };
@@ skipping 325 matching lines @@
     updateCachedAttributeValuesIfNeeded();
     return m_cachedHasInheritedPresentationalRole;
 }
 
 bool AXObject::isPresentationalChild() const
 {
     updateCachedAttributeValuesIfNeeded();
     return m_cachedIsPresentationalChild;
 }
 
+bool AXObject::ancestorExposesActiveDescendant() const

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

To be correct, shouldn't we check the role of the ancestor too?

For example, if someone creates a role="grid" and then (incorrectly) puts a
role="option" inside it, that shouldn't return true, right?

+{
+    for (const AXObject* object = this; object; object = object->parentObjectUnignored()) {
+        if (object->supportsActiveDescendant()
+            && !object->getAttribute(aria_activedescendantAttr).isEmpty()) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 // Simplify whitespace, but preserve a single leading and trailing whitespace character if it's present.
 // static
 String AXObject::collapseWhitespace(const String& str)
 {
     StringBuilder result;
     if (!str.isEmpty() && isHTMLSpace<UChar>(str[0]))
         result.append(' ');
     result.append(str.simplifyWhiteSpace(isHTMLSpace<UChar>));
     if (!str.isEmpty() && isHTMLSpace<UChar>(str[str.length() - 1]))
         result.append(' ');
@@ skipping 283 matching lines @@
         return false;
 
     return equalIgnoringCase(getAttribute(aria_multilineAttr), "true");
 }
 
 bool AXObject::ariaPressedIsPresent() const
 {
     return !getAttribute(aria_pressedAttr).isEmpty();
 }
 
+bool AXObject::supportsActiveDescendant() const
+{
+    // According to the ARIA Spec, all ARIA composite widgets, ARIA text boxes
+    // and ARIA groups should be able to expose an active descendant.
+    // Implicitly, <input> and <textarea> elements should also have this ability.
+    switch (ariaRoleAttribute()) {
+    case ComboBoxRole:
+    case GridRole:
+    case GroupRole:
+    case ListBoxRole:
+    case MenuRole:
+    case MenuBarRole:
+    case RadioGroupRole:
+    case TabListRole:
+    case TextFieldRole:

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

You deleted toolbar and some others, but the ARIA spec specifically lists
toolbar, row, and rowgroup. Please double-check the spec again:

https://rawgit.com/w3c/aria/master/aria/aria.html#aria-activedescendant

+    case TreeRole:
+    case TreeGridRole:
+        return true;
+    default:
+        return false;
+    }
+}
+
 bool AXObject::supportsARIAAttributes() const
 {
     return isLiveRegion()
         || supportsARIADragging()
         || supportsARIADropping()
         || supportsARIAFlowTo()
         || supportsARIAOwns()
         || hasAttribute(aria_labelAttr);
 }
 
@@ skipping 693 matching lines @@
 
 DEFINE_TRACE(AXObject)
 {
     visitor->trace(m_children);
     visitor->trace(m_parent);
     visitor->trace(m_cachedLiveRegionRoot);
     visitor->trace(m_axObjectCache);
 }
 
 } // namespace blink