[gnome-shell] background: Remove the system noise content when not in use

[Jasper St. Pierre <jstpierre src gnome org>]

commit 7f3aadc1573589bd169e25a61987d94eb27e4129
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Dec 3 17:05:06 2013 -0500

    background: Remove the system noise content when not in use
    
    https://bugzilla.gnome.org/show_bug.cgi?id=719803

 js/ui/background.js |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/background.js b/js/ui/background.js
index 5f11e57..af69f9d 100644
--- a/js/ui/background.js
+++ b/js/ui/background.js
@@ -634,7 +634,13 @@ const SystemBackground = new Lang.Class({
                                           this.emit('loaded');
                                       })
                                     });
-    }
+
+        this.actor.connect('destroy', Lang.bind(this, this._onDestroy));
+    },
+
+    _onDestroy: function() {
+        this._cache.removeImageContent(this.actor.content);
+    },
 });
 Signals.addSignalMethods(SystemBackground.prototype);