Re-land: Add a window property to associate RWHVA with its child AX tree ID

ui/views/accessibility/ax_window_obj_wrapper.cc

 // Copyright 2014 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/ax_window_obj_wrapper.h"
 
 #include <stddef.h>
 
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_node_data.h"
+#include "ui/accessibility/platform/aura_window_properties.h"
 #include "ui/aura/window.h"
 #include "ui/views/accessibility/ax_aura_obj_cache.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
 AXWindowObjWrapper::AXWindowObjWrapper(aura::Window* window)
     : window_(window), is_alert_(false) {
   window->AddObserver(this);
 }
@@ skipping 26 matching lines @@
     out_children->push_back(AXAuraObjCache::GetInstance()->GetOrCreate(widget));
 }
 
 void AXWindowObjWrapper::Serialize(ui::AXNodeData* out_node_data) {
   out_node_data->id = GetID();
   out_node_data->role = is_alert_ ? ui::AX_ROLE_ALERT : ui::AX_ROLE_WINDOW;
   out_node_data->AddStringAttribute(ui::AX_ATTR_NAME,
                                     base::UTF16ToUTF8(window_->GetTitle()));
   out_node_data->state = 0;
   out_node_data->location = gfx::RectF(window_->bounds());
+
+  ui::AXTreeIDRegistry::AXTreeID child_ax_tree_id =
+      window_->GetProperty(ui::kChildAXTreeID);
+  if (child_ax_tree_id != ui::AXTreeIDRegistry::kNoAXTreeID)
+    out_node_data->AddIntAttribute(ui::AX_ATTR_CHILD_TREE_ID, child_ax_tree_id);
 }
 
 int32_t AXWindowObjWrapper::GetID() {
   return AXAuraObjCache::GetInstance()->GetID(window_);
 }
 
 void AXWindowObjWrapper::OnWindowDestroyed(aura::Window* window) {
   AXAuraObjCache::GetInstance()->Remove(window, nullptr);
 }
 
@@ skipping 13 matching lines @@
                                                const gfx::Rect& old_bounds,
                                                const gfx::Rect& new_bounds) {
   Widget* widget = Widget::GetWidgetForNativeView(window);
   if (widget) {
     widget->GetRootView()->NotifyAccessibilityEvent(
         ui::AX_EVENT_LOCATION_CHANGED, true);
   }
 }
 
 }  // namespace views