Added proper extensions for hosted documents.

chrome/browser/resources/file_manager/js/file_manager.js

 // 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.
 
 // Setting the src of an img to an empty string can crash the browser, so we
 // use an empty 1x1 gif instead.
 const EMPTY_IMAGE_URI = 'data:image/gif;base64,'
         + 'R0lGODlhAQABAPABAP///wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw%3D%3D';
 
 /**
@@ skipping 1780 matching lines @@
     this.updateSize_(div, entry);
     return div;
   };
 
   FileManager.prototype.updateSize_ = function(div, entry) {
     // Unlike other rtl languages, Herbew use MB and writes the unit to the
     // right of the number. We use css trick to workaround this.
     if (navigator.language == 'he')
       div.className = 'align-end-weakrtl';
     div.textContent = '...';
+    var self = this;
     cacheEntrySize(entry, function(entry) {
       if (entry.cachedSize_ == -1) {
         div.textContent = '';
+      } else if (entry.cachedSize_ == 0 &&
+                 self.getFileType(entry).type == 'hosted') {
+        div.textContent = '--';
       } else {
         div.textContent = util.bytesToSi(entry.cachedSize_);
       }
     }, null, true);
   };
 
   /**
    * Render the Type column of the detail table.
    *
    * @param {Entry} entry The Entry object to render.
@@ skipping 2134 matching lines @@
           });
       }, onError);
 
       function onError(err) {
         console.log('Error while checking free space: ' + err);
         setTimeout(doCheck, 1000 * 60);
       }
     }
   }
 })();