res/drawable/ic_arrow_back.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
    Copyright 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.
-->

<!-- This Icon is used in as the back icon on ActionBar. ActionBar hard code the icon layout and
  ~  does not provide a way to customize it. Here to center the icon in action bar, we make up
  ~  the margin by add the extra space in the icon itself -->
<vector
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="@dimen/icon_size"
    android:height="@dimen/icon_size"
    android:viewportHeight="24.0"
    android:viewportWidth="24.0">
    <path
        android:fillColor="?attr/iconColor"
        android:pathData="M20,11H7.83l5.59,-5.59L12,4l-8,8 8,8 1.41,-1.41L7.83,13H20v-2z"/>
</vector>