This is UI side unreadable device support.

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

 /*
  * Copyright (c) 2011 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.
  */
 
 /* Outer frame of the dialog. */
 body {
   -webkit-box-flex: 1;
   -webkit-box-orient: vertical;
@@ skipping 307 matching lines @@
   background-repeat: no-repeat;
   height: 24px;
   width: 24px;
 }
 
 /* Icon for files in the detail list. */
 .detail-icon[iconType="audio"] {
   background-image: url(../images/filetype_audio.png);
 }
 
+.detail-icon[iconType="device"] {
+  background-image: url(../images/filetype_device.png);
+}
+
 .detail-icon[iconType="doc"] {
   background-image: url(../images/filetype_doc.png);
 }
 
 .detail-icon[iconType="folder"] {
   background-image: url(../images/filetype_folder.png);
 }
 
 .detail-icon[iconType="html"] {
   background-image: url(../images/filetype_html.png);
@@ skipping 12 matching lines @@
 }
 
 .detail-icon[iconType="spreadsheet"] {
   background-image: url(../images/filetype_spreadsheet.png);
 }
 
 .detail-icon[iconType="text"] {
   background-image: url(../images/filetype_text.png);
 }
 
+.detail-icon[iconType="unreadable"] {
+  background-image: url(../images/filetype_unreadable_device.png);
+}
+
 .detail-icon[iconType="video"] {
   background-image: url(../images/filetype_video.png);
 }
 
 /* The filename text in the preview pane. */
 .preview-filename {
   -webkit-margin-start: 8px;
   color: #666;
   font-weight: bold;
   margin-top: 10px;
@@ skipping 152 matching lines @@
 /* Overlay pane covering the entire file manager window (e.g. image editor)*/
 .overlay-pane {
   position: absolute;
   top: 0;
   left: 0;
   width: 100%;
   height: 100%;
   border: none;
   z-index: 100;
 }