[metacity/gnome-3-18] compositor: add error trap in free_win

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 1243d34816398ec9014115d4582a83ec5b84d5d0
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Wed May 25 14:43:30 2016 +0300

    compositor: add error trap in free_win
    
    It seems that picture might be destroyed with window if it is
    created by passing window id as drawable to XRenderCreatePicture.
    
    Add error trap around XRenderFreePicture to avoid Metacity crash
    with RenderBadPicture error.
    
    https://bugs.launchpad.net/ubuntu/+source/metacity/+bug/1582687

 src/compositor/compositor-xrender.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/compositor/compositor-xrender.c b/src/compositor/compositor-xrender.c
index 11bc528..c7d5128 100644
--- a/src/compositor/compositor-xrender.c
+++ b/src/compositor/compositor-xrender.c
@@ -1957,7 +1957,10 @@ free_win (MetaCompWindow *cw,
 
   if (cw->picture)
     {
+      meta_error_trap_push (display);
       XRenderFreePicture (xdisplay, cw->picture);
+      meta_error_trap_pop (display, FALSE);
+
       cw->picture = None;
     }