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 1237 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 {

[dmazzoni, 2017/05/19 19:54:04]

Should this check for the right type of container?

I.e. if you're on an option it should only walk
up to a container listbox, not a grid or toolbar.

Also, even though the spec seems to imply that
containers can have descendants anywhere, in many
cases the descendants have to be immediate children
for it to work on most platforms.

So the listitem has to be an immediate child of the
list, for example, or a group in some cases. You
can't have another non-presentational object in-between.

+  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