Add two command-line parameters and one bug fix for the layout test analyzer.

media/tools/layout_tests/layouttest_analyzer_helpers_unittest.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 copy
 import os
 import pickle
 import unittest
 
 import layouttest_analyzer_helpers
 
 
 class TestLayoutTestAnalyzerHelpers(unittest.TestCase):
 
   def testFindLatestTime(self):
     time_list = ['2011-08-18-19', '2011-08-18-22', '2011-08-18-21',
-                 '2012-01-11-21']
+                 '2012-01-11-21', '.foo']
     self.assertEquals(layouttest_analyzer_helpers.FindLatestTime(time_list),
                       '2012-01-11-21')
 
+  def testFindLatestTimeWithEmptyList(self):
+    time_list = []
+    self.assertEquals(layouttest_analyzer_helpers.FindLatestTime(time_list),
+                      None)
+
+  def testFindLatestTimeWithNoValidStringInList(self):
+    time_list = ['.foo1', '232232']
+    self.assertEquals(layouttest_analyzer_helpers.FindLatestTime(time_list),
+                      None)
+
   def GenerateTestDataWholeAndSkip(self):
     """You should call this method if you want to generate test data."""
     file_path = os.path.join('test_data', 'base')
     analyzerResultMapBase = (
         layouttest_analyzer_helpers.AnalyzerResultMap.Load(file_path))
     # Remove this first part
     m = analyzerResultMapBase.result_map['whole']
     del m['media/video-source-type.html']
     m = analyzerResultMapBase.result_map['skip']
     del m['media/track/track-webvtt-tc004-magicheader.html']
@@ skipping 61 matching lines @@
     file_path = os.path.join('test_data', 'base')
     analyzerResultMapBase = (
         layouttest_analyzer_helpers.AnalyzerResultMap.Load(file_path))
     self.assertEquals(
         len(analyzerResultMapBase.GetListOfBugsForNonSkippedTests().keys()),
         10)
 
 
 if __name__ == '__main__':
   unittest.main()