chrome/android/java/res/drawable/infobar_close_bg.xml

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

<!-- Copyright 2013 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.
-->

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:state_pressed="false"
        android:state_focused="false"
        android:drawable="@android:color/transparent" />
    <item
        android:state_pressed="false"
        android:state_focused="true"
        android:drawable="@drawable/infobar_close_button_focused" />
    <item
        android:drawable="@drawable/infobar_close_button_pressed" />
</selector>