In case of search add "Searching..." string to the spinner in the center.

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.col-resize * {
   cursor: col-resize !important;
 }
 
 /* Outer frame of the dialog. */
 body {
@@ skipping 504 matching lines @@
   height: 22px;
   left: 50%;
   margin-left: -11px;
   margin-top: -11px;
   opacity: 0.5;
   position: absolute;
   top: 50%;
   width: 22px;
 }
 
+#spinner-container {
+  -webkit-box-align: center;
+  -webkit-box-pack: center;
+  bottom: 0;
+  display: -webkit-box;
+  left: 0;
+  position: absolute;
+  right: 0;
+  top: 0;
+}
+
+#spinner-with-text {
+  background-image: url('../images/common/spinner.svg');
+  background-repeat: no-repeat;
+  font-size: 16px;
+  height: 22px;
+  min-width: 22px;
+  opacity: 0.6;
+  padding-left: 26px;
+}
+
 .downloads-warning {
   -webkit-box-align: center;
   -webkit-box-orient: horizontal;
   -webkit-transition: height 70ms linear;
   background-color: #f0f0f0;
   background-image: -webkit-image-set(
     url('../images/files/ui/warning_icon_square.png') 1x,
     url('../images/files/ui/2x/warning_icon_square.png') 2x);
   background-position: 15px center;
   background-repeat: no-repeat;
@@ skipping 872 matching lines @@
   width: 50%;
 }
 
 #list-container .table-header-inner {
   height: 100%;
 }
 
 #list-container .table-header-cell:hover {
   background-color: #f2f2f2;
 }