chromium/components/browser_ui/widget/android/java/res/layout/indeterminate_progress_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
Copyright 2016 The Chromium Authors
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file.
-->

<ProgressBar xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:indeterminate="true"
    android:gravity="center_horizontal|center_vertical" />