diff -r 000000000000 -r 6474c204b198 toolkit/devtools/apps/Devices.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/devtools/apps/Devices.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,43 @@
+/* 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";
+
+Components.utils.import("resource://gre/modules/devtools/event-emitter.js");
+
+const EXPORTED_SYMBOLS = ["Devices"];
+
+let addonInstalled = false;
+
+const Devices = {
+  _devices: {},
+
+  get helperAddonInstalled() {
+    return addonInstalled;
+  },
+  set helperAddonInstalled(v) {
+    addonInstalled = v;
+    this.emit("addon-status-updated", v);
+  },
+
+  register: function (name, device) {
+    this._devices[name] = device;
+    this.emit("register");
+  },
+
+  unregister: function (name) {
+    delete this._devices[name];
+    this.emit("unregister");
+  },
+
+  available: function () {
+    return Object.keys(this._devices).sort();
+  },
+
+  getByName: function (name) {
+    return this._devices[name];
+  }
+};
+
+EventEmitter.decorate(Devices);