Round corners for 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 204 matching lines @@
 .dialog-container {
   -webkit-box-align: stretch;
   -webkit-box-flex: 1;
   -webkit-box-orient: horizontal;
   background-color: white;  /* Makes #drag-container invisible. */
   display: -webkit-box;
   overflow: hidden;
   position: relative;
 }
 
+body[new-ui] .dialog-container {
+  -webkit-border-radius: 2px;
+}
+
 /* List/grid and preview are inside this container. */
 .dialog-main {
   -webkit-box-align: stretch;
   -webkit-box-flex: 1;
   -webkit-box-orient: vertical;
   display: -webkit-box;
 }
 
 /* Directory tree at the left. */
 .dialog-sidebar {
@@ skipping 1778 matching lines @@
 }
 
 list.autocomplete-suggestions[hasElementFocus] > [selected],
 list.autocomplete-suggestions[hasElementFocus] > [lead],
 list.autocomplete-suggestions:not([hasElementFocus]) > [selected],
 list.autocomplete-suggestions:not([hasElementFocus]) > [lead] {
   background-color: rgb(238, 238, 238);
   background-image: none;
   border: 1px solid white;
 }