Ensure fake alert window attached to AXAura tree and refine alert dialog output

chrome/browser/ui/aura/accessibility/ax_root_obj_wrapper.cc

Index: chrome/browser/ui/aura/accessibility/ax_root_obj_wrapper.cc
diff --git a/chrome/browser/ui/aura/accessibility/ax_root_obj_wrapper.cc b/chrome/browser/ui/aura/accessibility/ax_root_obj_wrapper.cc
index c8b3e9cd4fba705277ebc949587702083380a58c..5f2aa9fc302fe98f0cf62fc6f7d363220baccd24 100644
--- a/chrome/browser/ui/aura/accessibility/ax_root_obj_wrapper.cc
+++ b/chrome/browser/ui/aura/accessibility/ax_root_obj_wrapper.cc
@@ -46,6 +46,8 @@ views::AXAuraObjWrapper* AXRootObjWrapper::GetParent() {
 void AXRootObjWrapper::GetChildren(
     std::vector<views::AXAuraObjWrapper*>* out_children) {
   views::AXAuraObjCache::GetInstance()->GetTopLevelWindows(out_children);
+  out_children->push_back(
+      views::AXAuraObjCache::GetInstance()->GetOrCreate(alert_window_));
 }
 
 void AXRootObjWrapper::Serialize(ui::AXNodeData* out_node_data) {