[filemanager] Fix startup initialization: set current root dir before updating roots.

chrome/browser/resources/file_manager/js/directory_model.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.
 
 // If directory files changes too often, don't rescan directory more than once
 // per specified interval
 var SIMULTANEOUS_RESCAN_INTERVAL = 1000;
 // Used for operations that require almost instant rescan.
 var SHORT_RESCAN_INTERVAL = 100;
 
@@ skipping 752 matching lines @@
   function onScanComplete() {
     if (opt_callback)
       opt_callback();
     // For tests that open the dialog to empty directories, everything
     // is loaded at this point.
     chrome.test.sendMessage('directory-change-complete');
   }
   this.clearAndScan_(new DirectoryContentsBasic(this.currentFileListContext_,
                                                 dirEntry),
                      onScanComplete.bind(this));
+  this.currentDirByRoot_[this.getCurrentRootPath()] = dirEntry.fullPath;
   this.updateRootsListSelection_();
-  this.currentDirByRoot_[this.getCurrentRootPath()] = dirEntry.fullPath;
 };
 
 /**
  * Change the current directory to the directory represented by a
  * DirectoryEntry.
  *
  * Dispatches the 'directory-changed' event when the directory is successfully
  * changed.
  *
  * @private
@@ skipping 619 matching lines @@
         }.bind(this));
   }
 };
 
 /**
  * @return {DirectoryEntry} Current watched directory entry.
  */
 FileWatcher.prototype.getWatchedDirectoryEntry = function() {
   return this.watchedDirectoryEntry_;
 };