diff -r 000000000000 -r 6474c204b198 mobile/android/components/WebappsUpdateTimer.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/components/WebappsUpdateTimer.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,65 @@
+/* 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/. */
+
+/**
+ * This component triggers a periodic webapp update check.
+ */
+
+"use strict";
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/WebappManager.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+function log(message) {
+  // We use *dump* instead of Services.console.logStringMessage so the messages
+  // have the INFO level of severity instead of the ERROR level.  And we don't
+  // append a newline character to the end of the message because *dump* spills
+  // into the Android native logging system, which strips newlines from messages
+  // and breaks messages into lines automatically at display time (i.e. logcat).
+  dump(message);
+}
+
+function WebappsUpdateTimer() {}
+
+WebappsUpdateTimer.prototype = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsITimerCallback,
+                                         Ci.nsISupportsWeakReference]),
+  classID: Components.ID("{8f7002cb-e959-4f0a-a2e8-563232564385}"),
+
+  notify: function(aTimer) {
+    if (Services.prefs.getIntPref("browser.webapps.checkForUpdates") == 0) {
+      // Do nothing, because updates are disabled.
+      log("Webapps update timer invoked in webapp process; ignoring.");
+      return;
+    }
+
+    // If we are offline, wait to be online to start the update check.
+    if (Services.io.offline) {
+      log("network offline for webapp update check; waiting");
+      Services.obs.addObserver(this, "network:offline-status-changed", true);
+      return;
+    }
+
+    log("periodic check for webapp updates");
+    WebappManager.checkForUpdates();
+  },
+
+  observe: function(aSubject, aTopic, aData) {
+    if (aTopic !== "network:offline-status-changed" || aData !== "online") {
+      return;
+    }
+
+    log("network back online for webapp update check; commencing");
+    // TODO: observe pref to do this only on wifi.
+    Services.obs.removeObserver(this, "network:offline-status-changed");
+    WebappManager.checkForUpdates();
+  }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([WebappsUpdateTimer]);