pt 1 in reviving the android build (copied from pm 28a1, wish me luck)

mobile/android/base/java/org/mozilla/gecko/GeckoPresentationDisplay.java

@@ -0,0 +1,22 @@
+/* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-
+ * 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;
+
+import org.json.JSONObject;
+import org.mozilla.gecko.util.EventCallback;
+
+/**
+ * Wrapper for MediaRouter types supported by Android to use for
+ * Presentation API, such as Chromecast, Miracast, etc.
+ */
+interface GeckoPresentationDisplay {
+    /**
+     * Can return null.
+     */
+    JSONObject toJSON();
+    void start(EventCallback callback);
+    void stop(EventCallback callback);
+}