Use the pyauto API to get the default download directory since XP has a

functional/enterprise.py

 #!/usr/bin/python
 # Copyright (c) 2011 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.
 
 import logging
 import os
 import subprocess
 import re
 
@@ skipping 525 matching lines @@
         self.FindInPage('encrypted.google.com', tab_index=0)['match_count'],
         msg='SPDY is not enabled.')
 
   def testSetDownloadDirectory(self):
     """Verify that the downloads directory and prompt for download preferences
     can be modified.
     """
     if self.GetBrowserInfo()['properties']['branding'] != 'Google Chrome':
       return
     if self.IsWin():
-      download_default_dir = os.path.join(os.getenv('USERPROFILE'),'Downloads')
+      download_default_dir = self.GetDownloadDirectory().value()
       self.assertEqual(download_default_dir,
         self.GetPrefsInfo().Prefs()['download']['default_directory'],
         msg='Downloads directory is not set correctly.')
       # Check for changing the download directory location
       self.SetPrefs(pyauto.kDownloadDefaultDirectory,
                                 os.getenv('USERPROFILE'))
     elif self.IsLinux():
       download_default_dir = os.path.join(os.getenv('HOME'), 'Downloads')
       self.assertEqual(download_default_dir,
         self.GetPrefsInfo().Prefs()['download']['default_directory'],
@@ skipping 25 matching lines @@
       return
     url = self.GetFileURLForDataPath('plugin', 'java_new.html')
     self.NavigateToURL(url)
     self.assertTrue(self.WaitForInfobarCount(1))
     pid = self._GetPluginPID('Java')
     self.assertFalse(pid, 'There is a plugin process for java')
 
 
 if __name__ == '__main__':
   pyauto_functional.Main()