diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/extensions/test/xpcshell/test_default_providers_pref.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_default_providers_pref.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Tests the extensions.defaultProviders.enabled pref which turns
+// off the default XPIProvider and LightweightThemeManager.
+
+function run_test() {
+  Services.prefs.setBoolPref("extensions.defaultProviders.enabled", false);
+  createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "1.9.2");
+  startupManager();
+  do_check_false(AddonManager.isInstallEnabled("application/x-xpinstall"));
+  Services.prefs.clearUserPref("extensions.defaultProviders.enabled");
+}