[gnome-shell] gtk-embed: Don't try to compare with unrealized window

[Jonas Ådahl <jadahl src gnome org>]

commit c131c44ef64e4d98f1a8d8688cb41078f60c2239
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Dec 15 19:34:10 2016 +0800

    gtk-embed: Don't try to compare with unrealized window
    
    After having embedded a Gtk window, we start to listen for the
    corresponding MetaWindow to know when it has been mapped by the
    compositor. If the embedder does not realize the window immediately,
    and some other window is created and mapped before the embedder
    realizes the window, we would prior to this patch try to dereference
    the not created GdkWindow. Fix this by NULL checking the GdkWindow
    before dereferencing. We will never miss the needed MetaWindow creation
    since it can not have been mapped have it not yet been realized.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=776130

 src/shell-gtk-embed.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/shell-gtk-embed.c b/src/shell-gtk-embed.c
index 3f30613..176b413 100644
--- a/src/shell-gtk-embed.c
+++ b/src/shell-gtk-embed.c
@@ -66,7 +66,7 @@ shell_gtk_embed_window_created_cb (MetaDisplay   *display,
   Window xwindow = meta_window_get_xwindow (window);
   GdkWindow *gdk_window = gtk_widget_get_window (GTK_WIDGET (priv->window));
 
-  if (xwindow == gdk_x11_window_get_xid (gdk_window))
+  if (gdk_window && xwindow == gdk_x11_window_get_xid (gdk_window))
     {
       ClutterActor *window_actor =
         CLUTTER_ACTOR (meta_window_get_compositor_private (window));