diff -r 000000000000 -r 6474c204b198 js/xpconnect/idl/nsIJSRuntimeService.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/idl/nsIJSRuntimeService.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+[ptr] native JSRuntime(JSRuntime);
+[ptr] native JSContext(JSContext);
+native xpcGCCallback(xpcGCCallback);
+native xpcContextCallback(xpcContextCallback);
+
+%{C++
+
+#include "jsapi.h"  // for JSGCStatus
+
+typedef void
+(* xpcGCCallback)(JSGCStatus status);
+
+typedef bool
+(* xpcContextCallback)(JSContext* cx, unsigned operation);
+
+%}
+
+interface nsIBackstagePass;
+
+[uuid( 2ac111f2-e492-488e-85df-353c453e98f3)]
+interface nsIJSRuntimeService : nsISupports
+{
+    readonly attribute JSRuntime        runtime;
+
+    /**
+     * Register additional GC callback which will run after the
+     * standard XPConnect callback.
+     */
+    [noscript, notxpcom] void registerGCCallback(in xpcGCCallback func);
+    [noscript, notxpcom] void unregisterGCCallback(in xpcGCCallback func);
+
+    /**
+     * Register additional context callback which will run after the
+     * standard XPConnect callback.
+     */
+    [noscript, notxpcom] void registerContextCallback(in xpcContextCallback func);
+    [noscript, notxpcom] void unregisterContextCallback(in xpcContextCallback func);
+};