[mutter] x11-selection: Plug MetaSelectionSourceX11 leak

[Robert Mader <rmader src gnome org>]

commit 8e6821bc6586c9bd8c917cc37c40686c28ca95ad
Author: Sebastian Keller <skeller src gnome org>
Date:   Sat Jan 11 03:31:02 2020 +0100

    x11-selection: Plug MetaSelectionSourceX11 leak
    
    meta_selection_source_x11_new_finish() transfers the ownership of the
    selection source, but source_new_cb() was not freeing it.
    
    Fixes https://gitlab.gnome.org/GNOME/mutter/issues/998
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/1001

 src/x11/meta-x11-selection.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/x11/meta-x11-selection.c b/src/x11/meta-x11-selection.c
index 17b0c1e29..fbb46d680 100644
--- a/src/x11/meta-x11-selection.c
+++ b/src/x11/meta-x11-selection.c
@@ -298,6 +298,7 @@ source_new_cb (GObject      *object,
     {
       meta_selection_set_owner (selection, selection_type, source);
       g_set_object (&x11_display->selection.owners[selection_type], source);
+      g_object_unref (source);
     }
   else if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
     {