[chromeos] Make the doc viewing test more robust

chrome/test/functional/doc_viewing.py

 #!/usr/bin/env python
 # 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.
 
 import os
 
 import pyauto_functional  # must be imported before pyauto
 
 import chromeos.file_browser
@@ skipping 34 matching lines @@
     path = os.path.abspath(os.path.join(self.DataDir(),
                                         'pyauto_private', 'office'))
     # Copy sample files to Downloads directory.
     for (path, dirs, private_office_files) in os.walk(path):
       # Open sample files: .ppt, .pptx, .doc, .docx, xls, xlsx.
       for fname in private_office_files:
         test_utils.CopyFileFromDataDirToDownloadDir(self, os.path.join(path,
                                                                        fname))
         file_browser = self._GetFullPageFileBrowser()
         self.assertTrue(file_browser, msg='File browser failed to initialize.')
-        self.assertTrue(file_browser.Select(fname),
+
+        def _SelectFile():
+          try:
+            file_browser.Select(fname)
+            return True
+          except AssertionError:
+            return False
+
+        self.assertTrue(self.WaitUntil(_SelectFile),
                         msg='"%s" does not exist.' % fname)
         file_browser.ExecuteDefaultTask()
         self.assertTrue(self.WaitUntil(self.GetActiveTabTitle,
                         expect_retval=fname),
                         msg='"%s" does not open.' % fname)
         # Close the document viewing tab after use.
         self.CloseTab(tab_index=1)
 
 
 if __name__ == '__main__':
   pyauto_functional.Main()