filemanager: Update the icons in the left nav.

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 237 matching lines @@
 }
 
 li.root-item > .root-label {
   -webkit-box-flex: 1;
   margin-right: 5px;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
 
-.root-label {
-  -webkit-padding-start: 38px;
-  background-position: left center;
+.volume-icon {
+  background-position: center center;
   background-repeat: no-repeat;
+  height: 24px;
+  width: 24px;
 }
 
 div.root-eject {
   /* The transition commented out to work around crbug.com/157813 */
   /*-webkit-transition: opacity 70ms linear;*/
   background-image: -webkit-image-set(
     url('../images/files/ui/eject.png') 1x,
     url('../images/files/ui/2x/eject.png') 2x);
   background-position: center center;
   background-repeat: no-repeat;
@@ skipping 1361 matching lines @@
 
 #default-action-dialog {
   min-width: 300px;
   width: auto;
 }
 
 .drive-welcome-wrapper {
   /* drive_welcome.css will override it once loaded. */
   display: none;
 }