Selection follows focus/activedescendant in single selection containers

third_party/WebKit/Source/modules/accessibility/AXObjectImpl.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 756 matching lines @@
   UpdateCachedAttributeValuesIfNeeded();
   return cached_ancestor_exposes_active_descendant_;
 }
 
 bool AXObjectImpl::ComputeAncestorExposesActiveDescendant() const {
   const AXObjectImpl* parent = ParentObjectUnignored();
   if (!parent)
     return false;
 
   if (parent->SupportsActiveDescendant() &&
-      !parent->GetAttribute(aria_activedescendantAttr).IsEmpty()) {
+      parent->HasAttribute(aria_activedescendantAttr)) {
     return true;
   }
 
   return parent->AncestorExposesActiveDescendant();
 }
 
 // Simplify whitespace, but preserve a single leading and trailing whitespace
 // character if it's present.
 // static
 String AXObjectImpl::CollapseWhitespace(const String& str) {
@@ skipping 460 matching lines @@
 
 AXObjectImpl* AXObjectImpl::ParentObjectUnignored() const {
   AXObjectImpl* parent;
   for (parent = ParentObject(); parent && parent->AccessibilityIsIgnored();
        parent = parent->ParentObject()) {
   }
 
   return parent;
 }
 
+// Container widgets are those that a user tabs into and arrows around
+// sub-widgets
+bool AXObjectImpl::IsContainerWidget() const {
+  switch (RoleValue()) {
+    case kComboBoxRole:
+    case kGridRole:
+    case kListBoxRole:
+    case kMenuBarRole:
+    case kMenuRole:
+    case kRadioGroupRole:
+    case kSpinButtonRole:
+    case kTabListRole:
+    case kToolbarRole:
+    case kTreeGridRole:
+    case kTreeRole:
+      return true;
+    default:
+      return false;
+  }
+}
+
+AXObjectImpl* AXObjectImpl::ContainerWidget() const {
+  AXObjectImpl* ancestor = ParentObjectUnignored();
+  while (ancestor && !ancestor->IsContainerWidget())
+    ancestor = ancestor->ParentObjectUnignored();
+
+  return ancestor;
+}
+
 void AXObjectImpl::UpdateChildrenIfNecessary() {
   if (!HasChildren())
     AddChildren();
 }
 
 void AXObjectImpl::ClearChildren() {
   // Detach all weak pointers from objects to their parents.
   for (const auto& child : children_)
     child->DetachFromParent();
 
@@ skipping 754 matching lines @@
 }
 
 DEFINE_TRACE(AXObjectImpl) {
   visitor->Trace(children_);
   visitor->Trace(parent_);
   visitor->Trace(cached_live_region_root_);
   visitor->Trace(ax_object_cache_);
 }
 
 }  // namespace blink