Various fixes for aria-activedescendant.

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

Index: third_party/WebKit/Source/modules/accessibility/AXObject.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXObject.cpp b/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
index fee64c6d8d0827216bf91915953c1d68b30addb7..bfac4a5347c57cf13b793f5b59ee3e49aaa13fd9 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
@@ -330,7 +330,8 @@ const char* ariaWidgets[] = {
     "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",
@@ -676,6 +677,18 @@ bool AXObject::isPresentationalChild() const
     return m_cachedIsPresentationalChild;
 }
 
+bool AXObject::ancestorExposesActiveDescendant() const
+{
+    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)
@@ -979,6 +992,32 @@ 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 RowRole:
+    case SearchBoxRole:
+    case TabListRole:
+    case TextFieldRole:
+    case ToolbarRole:
+    case TreeRole:
+    case TreeGridRole:
+        return true;
+    default:
+        return false;
+    }
+}
+
 bool AXObject::supportsARIAAttributes() const
 {
     return isLiveRegion()