packages/SystemUI/res/drawable/pip_expand.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
Copyright (C) 2017 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.
-->
<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="36dp"
    android:height="36dp"
    android:viewportWidth="36"
    android:viewportHeight="36">

    <path
        android:pathData="M0 0h36v36H0z" />
    <path
        android:fillColor="#FFFFFF"
        android:pathData="M10 21H7v8h8v-3h-5v-5zm-3-6h3v-5h5V7H7v8zm19 11h-5v3h8v-8h-3v5zM21
7v3h5v5h3V7h-8z" />
</vector>