Fix crash trying to fire event on destroying Widget with no root view

ui/views/accessibility/ax_window_obj_wrapper.cc

Index: ui/views/accessibility/ax_window_obj_wrapper.cc
diff --git a/ui/views/accessibility/ax_window_obj_wrapper.cc b/ui/views/accessibility/ax_window_obj_wrapper.cc
index 0f08a3c8434892d11c5071a577d14714744b795b..113f3646ca64700ee0e8452dc5ea34603014d444 100644
--- a/ui/views/accessibility/ax_window_obj_wrapper.cc
+++ b/ui/views/accessibility/ax_window_obj_wrapper.cc
@@ -103,7 +103,7 @@ void AXWindowObjWrapper::OnWindowBoundsChanged(aura::Window* window,
   AXAuraObjCache::GetInstance()->FireEvent(this, ui::AX_EVENT_LOCATION_CHANGED);
 
   Widget* widget = Widget::GetWidgetForNativeView(window);
-  if (widget) {
+  if (widget && widget->GetRootView()) {
     widget->GetRootView()->NotifyAccessibilityEvent(
         ui::AX_EVENT_LOCATION_CHANGED, true);
   }