[chromeos] Make the doc viewing test more robust

chrome/test/functional/doc_viewing.py

Index: chrome/test/functional/doc_viewing.py
diff --git a/chrome/test/functional/doc_viewing.py b/chrome/test/functional/doc_viewing.py
index 0a0821d128c288a7fdb194638b07d80ca408898d..4e21178ea5e2bdc7f502f9cdd0aeafdd79253915 100755
--- a/chrome/test/functional/doc_viewing.py
+++ b/chrome/test/functional/doc_viewing.py
@@ -52,7 +52,15 @@ class DocViewingTest(pyauto.PyUITest):
                                                                        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,