Add window buttons (close and maximize) to the Files.app's new UI.

chrome/browser/resources/file_manager/css/file_manager.css

 /* Copyright (c) 2012 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. */
 
 html {
   height: 100%;
 }
 
 html.col-resize * {
   cursor: col-resize !important;
@@ skipping 713 matching lines @@
     url('../images/files/ui/breadcrumb-separator.png') 1x,
     url('../images/files/ui/2x/breadcrumb-separator.png') 2x);
   background-position: center center;
   background-repeat: no-repeat;
   height: 10px;
   overflow: hidden;
   width: 25px;
 }
 
 body[new-ui] .dialog-header .buttonbar button {
+  -webkit-margin-start: 0;
   background-image: none;
   background-position: center;
   background-repeat: no-repeat;
   min-width: 29px;
   padding: 0;
   width: 29px;
 }
 
 body[new-ui] .dialog-header button:not(:hover):not(focus) {
   background-color: transparent;
@@ skipping 1454 matching lines @@
   background-image: -webkit-image-set(
     url('../images/files/ui/new-ui/button_mosaic_view.png') 1x,
     url('../images/files/ui/new-ui/2x/button_mosaic_view.png') 2x);
 }
 
 body[new-ui] #iframe-drag-area {
   -webkit-app-region: drag;
   height: 45px;
   left: 64px;
   position: absolute;
-  right: 0;
+  right: 70px;
   top: 0;
+  width: auto;
   z-index: 101;
 }