Verifies WindowClosing() is invoked only once when a window is

ui/views/widget/desktop_aura/desktop_root_window_host_linux.cc

Index: ui/views/widget/desktop_aura/desktop_root_window_host_linux.cc
diff --git a/ui/views/widget/desktop_aura/desktop_root_window_host_linux.cc b/ui/views/widget/desktop_aura/desktop_root_window_host_linux.cc
index 3df42ec9b4b28cbb8b975393beb92d84ee60f891..6175ebd54963075c0e44a2535671e1f6fa114b6f 100644
--- a/ui/views/widget/desktop_aura/desktop_root_window_host_linux.cc
+++ b/ui/views/widget/desktop_aura/desktop_root_window_host_linux.cc
@@ -337,6 +337,9 @@ void DesktopRootWindowHostLinux::Close() {
 void DesktopRootWindowHostLinux::CloseNow() {
   if (xwindow_ == None)
     return;
+
+  native_widget_delegate_->OnNativeWidgetDestroying();
+
   // Remove the event listeners we've installed. We need to remove these
   // because otherwise we get assert during ~RootWindow().
   desktop_native_widget_aura_->root_window_event_filter()->RemoveHandler(