Add a crash for debugging when we get into a bad state.

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
index 1d3cbd7f8773b6c052e5c2115c3bec5ea79338c5..c174531b37b36cdb883ef98afb4f88bf143e79e6 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
@@ -259,6 +259,10 @@ class VIEWS_EXPORT DesktopWindowTreeHostX11
   // Is the window mapped to the screen?
   bool window_mapped_;
 
+  // Keeps track of whether we have ever mapped/withdrawn this
+  // window. Debugging information in trying to track down crbug.com/381732.
+  bool x_map_window_was_called_ = false;
+
   // The bounds of |xwindow_|.
   gfx::Rect bounds_in_pixels_;