[gnome-control-center] printers: Use dialog cancellable in async call

[Robert Ancell <rancell src gnome org>]

commit e20fd185c89a8f3fcb2f52b10e597a859ff1df32
Author: Robert Ancell <robert ancell canonical com>
Date:   Fri Nov 23 14:12:35 2018 +1300

    printers: Use dialog cancellable in async call
    
    Otherwise this could crash if the dialog is destroyed before the PPD is set.

 panels/printers/pp-details-dialog.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/panels/printers/pp-details-dialog.c b/panels/printers/pp-details-dialog.c
index 00e0087b5..cf74d92b5 100644
--- a/panels/printers/pp-details-dialog.c
+++ b/panels/printers/pp-details-dialog.c
@@ -346,7 +346,7 @@ select_ppd_manually (GtkButton       *button,
         {
           printer_set_ppd_file_async (self->printer_name,
                                       ppd_filename,
-                                      NULL,
+                                      self->cancellable,
                                       set_ppd_cb,
                                       self);
         }