diff -r 000000000000 -r 6474c204b198 dom/activities/src/ActivityProxy.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/activities/src/ActivityProxy.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,104 @@
+/* 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.defineLazyServiceGetter(this, "cpmm",
+                                   "@mozilla.org/childprocessmessagemanager;1",
+                                   "nsISyncMessageSender");
+
+function debug(aMsg) {
+  //dump("-- ActivityProxy " + Date.now() + " : " + aMsg + "\n");
+}
+
+/**
+  * nsIActivityProxy implementation
+  * We keep a reference to the C++ Activity object, and
+  * communicate with the Message Manager to know when to
+  * fire events on it.
+  */
+function ActivityProxy() {
+  debug("ActivityProxy");
+  this.activity = null;
+  let inParent = Cc["@mozilla.org/xre/app-info;1"].getService(Ci.nsIXULRuntime)
+                   .processType == Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
+  debug("inParent: " + inParent);
+  Cu.import(inParent ? "resource://gre/modules/Webapps.jsm"
+                     : "resource://gre/modules/AppsServiceChild.jsm");
+}
+
+ActivityProxy.prototype = {
+  startActivity: function actProxy_startActivity(aActivity, aOptions, aWindow) {
+    debug("startActivity");
+
+    this.window = aWindow;
+    this.activity = aActivity;
+    this.id = Cc["@mozilla.org/uuid-generator;1"]
+                .getService(Ci.nsIUUIDGenerator)
+                .generateUUID().toString();
+    // Retrieve the app's manifest url from the principal, so that we can
+    // later notify when the activity handler called postResult or postError
+    let principal = aWindow.document.nodePrincipal;
+    let appId = principal.appId;
+    let manifestURL = (appId != Ci.nsIScriptSecurityManager.NO_APP_ID &&
+                       appId != Ci.nsIScriptSecurityManager.UNKNOWN_APP_ID)
+                        ? DOMApplicationRegistry.getManifestURLByLocalId(appId)
+                        : null;
+    cpmm.sendAsyncMessage("Activity:Start", { id: this.id,
+                                              options: {
+                                                name: aOptions.name,
+                                                data: aOptions.data
+                                              },
+                                              manifestURL: manifestURL,
+                                              pageURL: aWindow.document.location.href });
+
+    cpmm.addMessageListener("Activity:FireSuccess", this);
+    cpmm.addMessageListener("Activity:FireError", this);
+  },
+
+  receiveMessage: function actProxy_receiveMessage(aMessage) {
+    debug("Got message: " + aMessage.name);
+    let msg = aMessage.json;
+    if (msg.id != this.id)
+      return;
+    debug("msg=" + JSON.stringify(msg));
+
+    switch(aMessage.name) {
+      case "Activity:FireSuccess":
+        debug("FireSuccess");
+        Services.DOMRequest.fireSuccess(this.activity,
+                                        Cu.cloneInto(msg.result, this.window));
+        Services.obs.notifyObservers(null, "Activity:Success", null);
+        break;
+      case "Activity:FireError":
+        debug("FireError");
+        Services.DOMRequest.fireError(this.activity, msg.error);
+        Services.obs.notifyObservers(null, "Activity:Error", null);
+        break;
+    }
+    // We can only get one FireSuccess / FireError message, so cleanup as soon as possible.
+    this.cleanup();
+  },
+
+  cleanup: function actProxy_cleanup() {
+    debug("cleanup");
+    if (cpmm && !this.cleanedUp) {
+      cpmm.removeMessageListener("Activity:FireSuccess", this);
+      cpmm.removeMessageListener("Activity:FireError", this);
+    }
+    this.cleanedUp = true;
+  },
+
+  classID: Components.ID("{ba9bd5cb-76a0-4ecf-a7b3-d2f7c43c5949}"),
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIActivityProxy])
+}
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([ActivityProxy]);