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

ui/views/accessibility/native_view_accessibility_auralinux.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 "ui/views/accessibility/native_view_accessibility_auralinux.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 39 matching lines @@
       return;
 
     widgets_.push_back(widget);
     widget->AddObserver(this);
   }
 
   gfx::NativeViewAccessible GetNativeViewAccessible() {
     return platform_node_->GetNativeViewAccessible();
   }
 
-  //
-  // WidgetObserver overrides.
-  //
+  // WidgetObserver:
 
   void OnWidgetDestroying(Widget* widget) override {
     auto iter = std::find(widgets_.begin(), widgets_.end(), widget);
     if (iter != widgets_.end())
       widgets_.erase(iter);
   }
 
-  //
-  // ui::AXPlatformNodeDelegate overrides.
-  //
+  // ui::AXPlatformNodeDelegate:
 
   const ui::AXNodeData& GetData() override {
     return data_;
   }
 
+  gfx::NativeWindow GetTopLevelWidget() override { return nullptr; }
+
   gfx::NativeViewAccessible GetParent() override {
     return nullptr;
   }
 
   int GetChildCount() override {
     return static_cast<int>(widgets_.size());
   }
 
   gfx::NativeViewAccessible ChildAtIndex(int index) override {
     if (index < 0 || index >= GetChildCount())
@@ skipping 77 matching lines @@
 }
 
 gfx::NativeViewAccessible NativeViewAccessibilityAuraLinux::GetParent() {
   gfx::NativeViewAccessible parent = NativeViewAccessibility::GetParent();
   if (!parent)
     parent = AuraLinuxApplication::GetInstance()->GetNativeViewAccessible();
   return parent;
 }
 
 }  // namespace views