[mutter] x11-selection: Unref owners and cancellables on shutdown

[Robert Mader <rmader src gnome org>]

commit b41094ef5f70fe4511dd73b28d4075401d32a3d0
Author: Sebastian Keller <skeller gnome org>
Date:   Thu Jan 30 09:19:39 2020 +0100

    x11-selection: Unref owners and cancellables on shutdown
    
    Selection owners are set using g_set_object in source_new_cb, but that
    reference is never removed on shutdown.
    
    Similarly the cancellables created in handle_xfixes_selection_notify are
    never freed on shutdown.
    
    Fixes parts of https://gitlab.gnome.org/GNOME/mutter/issues/1006
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/1001

 src/x11/meta-x11-selection.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/src/x11/meta-x11-selection.c b/src/x11/meta-x11-selection.c
index fbb46d680..a93fa1585 100644
--- a/src/x11/meta-x11-selection.c
+++ b/src/x11/meta-x11-selection.c
@@ -442,10 +442,22 @@ void
 meta_x11_selection_shutdown (MetaX11Display *x11_display)
 {
   MetaDisplay *display = meta_get_display ();
+  guint i;
 
   g_signal_handlers_disconnect_by_func (meta_display_get_selection (display),
                                         owner_changed_cb,
                                         x11_display);
+
+  for (i = 0; i < META_N_SELECTION_TYPES; i++)
+    {
+      g_clear_object (&x11_display->selection.owners[i]);
+      if (x11_display->selection.cancellables[i])
+        {
+          g_cancellable_cancel (x11_display->selection.cancellables[i]);
+          g_clear_object (&x11_display->selection.cancellables[i]);
+        }
+    }
+
   if (x11_display->selection.xwindow != None)
     {
       XDestroyWindow (x11_display->xdisplay, x11_display->selection.xwindow);