diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/util/deprecate.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/util/deprecate.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,40 @@
+/* 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/. */
+
+"use strict";
+
+module.metadata = {
+  "stability": "experimental"
+};
+
+const { get, format } = require("../console/traceback");
+const { get: getPref } = require("../preferences/service");
+const PREFERENCE = "devtools.errorconsole.deprecation_warnings";
+
+function deprecateUsage(msg) {
+  // Print caller stacktrace in order to help figuring out which code
+  // does use deprecated thing
+  let stack = get().slice(2);
+
+  if (getPref(PREFERENCE)) 
+    console.error("DEPRECATED: " + msg + "\n" + format(stack));
+}
+exports.deprecateUsage = deprecateUsage;
+
+function deprecateFunction(fun, msg) {
+  return function deprecated() {
+    deprecateUsage(msg);
+    return fun.apply(this, arguments);
+  };
+}
+exports.deprecateFunction = deprecateFunction;
+
+function deprecateEvent(fun, msg, evtTypes) {
+  return function deprecateEvent(evtType) {
+  	if (evtTypes.indexOf(evtType) >= 0)
+      deprecateUsage(msg);
+    return fun.apply(this, arguments);
+  };
+}
+exports.deprecateEvent = deprecateEvent;