diff -r 000000000000 -r 6474c204b198 docshell/test/unit_ipc/test_pb_notification_ipc.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/docshell/test/unit_ipc/test_pb_notification_ipc.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+function run_test() {
+  var notifications = 0;
+  var obs = {
+    observe: function(aSubject, aTopic, aData) {
+      do_check_eq(aTopic, "last-pb-context-exited");
+      notifications++;
+    }
+  };
+  var os = Cc["@mozilla.org/observer-service;1"].getService(Ci.nsIObserverService);
+  os.addObserver(obs, "last-pb-context-exited", false);
+ 
+  run_test_in_child("../unit/test_pb_notification.js",
+                    function() {
+                      do_check_eq(notifications, 1);
+                      do_test_finished();
+                    });
+}
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