[gtk+/portal] Use g_clear_object

[Matthias Clasen <matthiasc src gnome org>]

commit 56c87d48b3621f3ebaafd8fc8fa8100afcd0c63a
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jul 6 20:54:47 2016 -0400

    Use g_clear_object
    
    Just a small cleanup.

 gtk/gtkfilechoosernativeportal.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkfilechoosernativeportal.c b/gtk/gtkfilechoosernativeportal.c
index c355601..ebff8fc 100644
--- a/gtk/gtkfilechoosernativeportal.c
+++ b/gtk/gtkfilechoosernativeportal.c
@@ -77,8 +77,7 @@ filechooser_portal_data_free (FilechooserPortalData *data)
       gtk_widget_destroy (data->grab_widget);
     }
 
-  if (data->self)
-    g_object_unref (data->self);
+  g_clear_object (&data->self);
 
   g_free (data->portal_handle);