Files.app: Added DragSelector class.

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 999 matching lines @@
 
 #detail-table > list,
 .thumbnail-grid {
   -webkit-box-flex: 1;
 }
 
 body[new-ui] .main-panel #detail-table > list {
   padding-bottom: 52px;  /* height of the preview panel */
 }
 
+body[new-ui] .main-panel #detail-table > list > .drag-selection-border {
+  -webkit-box-sizing: border-box;
+  background-color: rgba(255, 255, 255, 0.3);
+  border: 2px solid rgba(255, 255, 255, 0.6);
+  border-radius: 0; /* Override the style of cr.ui.List */
+  outline: 1px solid rgba(0, 0, 0, 0.1);
+  padding: 0; /* Override the style of cr.ui.List */
+  position: absolute;
+  z-index: 2;
+}
+
 .spinner {
   background-image: url('../images/common/spinner.svg');
   background-size: 100%;
   height: 22px;
   left: 50%;
   margin-left: -11px;
   margin-top: -11px;
   opacity: 0.5;
   position: absolute;
   top: 50%;
@@ skipping 1430 matching lines @@
 body[new-ui] #iframe-drag-area {
   -webkit-app-region: drag;
   height: 45px;
   left: 64px;
   position: absolute;
   right: 70px;
   top: 0;
   width: auto;
   z-index: 101;
 }