Fixed volume icons' alignment.

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 231 matching lines @@
 
 #roots-list li.root-item {
   -webkit-box-align: center;
   display: -webkit-box;
   line-height: 22px;  /* To accomodate for icons. */
   padding-left: 11px;
 }
 
 li.root-item > .root-label {
   -webkit-box-flex: 1;
-  margin-right: 5px;
+  margin: 0 2px;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
 
 .volume-icon {
-  background-position: center center;
+  background-position: center 2px;
   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,
@@ skipping 1364 matching lines @@
 
 #default-action-dialog {
   min-width: 300px;
   width: auto;
 }
 
 .drive-welcome-wrapper {
   /* drive_welcome.css will override it once loaded. */
   display: none;
 }