[mutter] background: fix task leak in load_file_async

[Ray Strode <halfline src gnome org>]

commit 5ed6e37e3c4c926039dc1ce0fc459e2aa2fd7036
Author: Ray Strode <rstrode redhat com>
Date:   Sun Mar 24 23:06:24 2013 -0400

    background: fix task leak in load_file_async
    
    g_task_run_in_thread takes its own reference to the
    task passed in, so we can unref the initial reference.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=696157

 src/compositor/meta-background.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/compositor/meta-background.c b/src/compositor/meta-background.c
index 7876d59..f75d881 100644
--- a/src/compositor/meta-background.c
+++ b/src/compositor/meta-background.c
@@ -1129,6 +1129,7 @@ meta_background_load_file_async (MetaBackground          *self,
     g_task_set_task_data (task, task_data, (GDestroyNotify) load_file_task_data_free);
 
     g_task_run_in_thread (task, (GTaskThreadFunc) load_file);
+    g_object_unref (task);
 }
 
 /**