Mac a11y: Add Help, TopLevelUIElement, and Window accessibility attributes.

ui/accessibility/platform/test_ax_node_wrapper.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/containers/hash_tables.h"
 #include "ui/accessibility/platform/test_ax_node_wrapper.h"
 
 namespace ui {
 
 namespace {
@@ skipping 53 matching lines @@
 }
 
 TestAXNodeWrapper::~TestAXNodeWrapper() {
   platform_node_->Destroy();
 }
 
 const AXNodeData& TestAXNodeWrapper::GetData() {
   return node_->data();
 }
 
+gfx::NativeWindow TestAXNodeWrapper::GetTopLevelWidget() {
+  return nullptr;
+}
+
 gfx::NativeViewAccessible TestAXNodeWrapper::GetParent() {
   TestAXNodeWrapper* parent_wrapper = GetOrCreate(tree_, node_->parent());
   return parent_wrapper ?
       parent_wrapper->ax_platform_node()->GetNativeViewAccessible() :
       nullptr;
 }
 
 int TestAXNodeWrapper::GetChildCount() {
   return node_->child_count();
 }
@@ skipping 32 matching lines @@
   return false;
 }
 
 TestAXNodeWrapper::TestAXNodeWrapper(AXTree* tree, AXNode* node)
     : tree_(tree),
       node_(node),
       platform_node_(AXPlatformNode::Create(this)) {
 }
 
 }  // namespace ui