diff -r 000000000000 -r 6474c204b198 b2g/components/ActivitiesGlue.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/b2g/components/ActivitiesGlue.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,74 @@
+/* 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"
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+XPCOMUtils.defineLazyModuleGetter(this, "SystemAppProxy",
+                                  "resource://gre/modules/SystemAppProxy.jsm");
+
+function ActivitiesDialog() {
+  this._id = 0;
+
+  this.activities = [];
+}
+
+ActivitiesDialog.prototype = {
+  run: function ap_run() {
+    let id = "activity-choice" + this._id++;
+    let activity = this.activities.shift();
+
+    let choices = [];
+    activity.list.forEach(function(item) {
+      choices.push({ manifest: item.manifest, icon: item.icon });
+    });
+
+
+    // Keep up the frond-end of an activity choice. The messages contains
+    // a list of {names, icons} for applications able to handle this particular
+    // activity. The front-end should display a UI to pick one.
+    let detail = {
+      type: "activity-choice",
+      id: id,
+      name: activity.name,
+      choices: choices
+    };
+
+    // Listen the resulting choice from the front-end. If there is no choice,
+    // let's return -1, which means the user has cancelled the dialog.
+    SystemAppProxy.addEventListener("mozContentEvent", function act_getChoice(evt) {
+      if (evt.detail.id != id)
+        return;
+
+      SystemAppProxy.removeEventListener("mozContentEvent", act_getChoice);
+      activity.callback.handleEvent(evt.detail.value !== undefined
+                                      ? evt.detail.value
+                                      : -1);
+    });
+
+    SystemAppProxy.dispatchEvent(detail);
+  },
+
+  chooseActivity: function ap_chooseActivity(aName, aActivities, aCallback) {
+    this.activities.push({
+      name: aName,
+      list: aActivities,
+      callback: aCallback
+    });
+    Services.tm.currentThread.dispatch(this, Ci.nsIEventTarget.DISPATCH_NORMAL);
+  },
+
+  classID: Components.ID("{70a83123-7467-4389-a309-3e81c74ad002}"),
+
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIActivityUIGlue, Ci.nsIRunnable])
+}
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([ActivitiesDialog]);
+