gecko/mobile/android/base/resources/menu/gecko_app_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- 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/. -->

<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/quit"
          android:icon="@drawable/ic_menu_quit"
          android:title="@string/quit"
          android:orderInCategory="10" />
</menu>