Fix crash when closing a window with an associated widget child

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"
@@ skipping 25 matching lines @@
   aura::Window::Windows children = window_->children();
   for (size_t i = 0; i < children.size(); ++i) {
     if (!children[i]->IsVisible())
       continue;
     out_children->push_back(
         AXAuraObjCache::GetInstance()->GetOrCreate(children[i]));
   }
 
   // Also consider any associated widgets as children.
   Widget* widget = Widget::GetWidgetForNativeView(window_);
-  if (widget)
+  if (widget && widget->IsVisible())
     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_->title()));
   out_node_data->state = 0;
   out_node_data->location = window_->bounds();
 }
 
 int32_t AXWindowObjWrapper::GetID() {
   return AXAuraObjCache::GetInstance()->GetID(window_);
 }
 
 void AXWindowObjWrapper::OnWindowDestroyed(aura::Window* window) {
   AXAuraObjCache::GetInstance()->Remove(window);
 }
 
 }  // namespace views