gecko-dev/mobile/android/base/resources/layout-large-land-v11/tabs_panel_footer.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/. -->

<merge xmlns:android="http://schemas.android.com/apk/res/android">

    <ImageButton android:id="@+id/add_tab"
                 android:layout_width="fill_parent"
                 android:layout_height="@dimen/browser_toolbar_height"
                 android:padding="14dip"
                 android:src="@drawable/tab_new_level"
                 android:contentDescription="@string/new_tab"
                 android:background="@drawable/action_bar_button_inverse"
                 android:gravity="center"/>

</merge>