Added proper extensions for hosted documents.

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.
  */
 
 /* Outer frame of the dialog. */
 body {
    -webkit-box-flex: 1;
    -webkit-box-orient: vertical;
@@ skipping 847 matching lines @@
 }
 
 .detail-icon[iconType="video"] {
   background-image: url(../images/filetype_video.png);
 }
 
 .detail-icon[iconType="word"] {
   background-image: url(../images/filetype_word.png);
 }
 
+.detail-icon[iconType="gdoc"] {
+  background-image: url(../images/filetype_doc.png);
+}
+
+.detail-icon[iconType="gsheet"] {
+  background-image: url(../images/filetype_spreadsheet.png);
+}
+
+.detail-icon[iconType="gslides"] {
+  background-image: url(../images/filetype_presentation.png);
+}
+
+.detail-icon[iconType="gdraw"] {
+  background-image: url(../images/filetype_drawing.png);
+}
+
+.detail-icon[iconType="gtable"] {
+  background-image: url(../images/filetype_table.png);
+}
+
 /* The filename text in the preview pane. */
 .preview-filename {
   -webkit-margin-start: 8px;
   color: #666;
   font-weight: bold;
   margin-top: 10px;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
@@ skipping 115 matching lines @@
   left: 0;
   width: 100%;
   height: 100%;
   border: none;
   z-index: 100;
 }
 
 menu.file-context-menu {
   z-index: 4;
 }