chrome/android/java/res/layout/indeterminate_progress_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2016 The Chromium Authors. All rights reserved.
     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" />