sdk/platforms/android-27/data/res/layout/tooltip.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
/*
** Copyright 2016, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
**     http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
-->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@android:id/message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/tooltip_margin"
        android:paddingStart="@dimen/tooltip_horizontal_padding"
        android:paddingEnd="@dimen/tooltip_horizontal_padding"
        android:paddingTop="@dimen/tooltip_vertical_padding"
        android:paddingBottom="@dimen/tooltip_vertical_padding"
        android:maxWidth="256dp"
        android:background="?android:attr/tooltipFrameBackground"
        android:textAppearance="@style/TextAppearance.Tooltip"
        android:textColor="?android:attr/tooltipForegroundColor"
        android:maxLines="3"
        android:ellipsize="end"
    />

</LinearLayout>