diff -r 000000000000 -r 6474c204b198 mobile/android/base/fxa/authenticator/FxAccountLoginDelegate.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/fxa/authenticator/FxAccountLoginDelegate.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,26 @@
+/* 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/. */
+
+package org.mozilla.gecko.fxa.authenticator;
+
+/**
+ * Abstraction around things that might need to be signalled to the user via UI,
+ * such as:
+ * <ul>
+ * <li>account not yet verified;</li>
+ * <li>account password needs to be updated;</li>
+ * <li>account key management required or changed;</li>
+ * <li>auth protocol has changed and Firefox needs to be upgraded;</li>
+ * </ul>
+ * etc.
+ * <p>
+ * Consumers of this code should differentiate error classes based on the types
+ * of the exceptions thrown. Exceptions that do not have special meaning are of
+ * type <code>FxAccountLoginException</code> with an appropriate
+ * <code>cause</code> inner exception.
+ */
+public interface FxAccountLoginDelegate {
+  public void handleError(FxAccountLoginException e);
+  public void handleSuccess(String assertion);
+}