Make changes to support bisect for android-chrome.

tools/auto_bisect/bisect_perf_regression_test.py

 # Copyright 2014 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 re
 import shutil
 import sys
 import unittest
 
@@ skipping 386 matching lines @@
     self.assertEqual(
         23634, source_control.GetCommitPosition(v8_rev, depot_path))
 
   def testGetCommitPositionForWebKit(self):
     bisect_instance = _GetBisectPerformanceMetricsInstance(DEFAULT_OPTIONS)
     wk_rev = 'a94d028e0f2c77f159b3dac95eb90c3b4cf48c61'
     depot_path = os.path.join(bisect_instance.src_cwd, 'third_party', 'WebKit')
     self.assertEqual(
         181660, source_control.GetCommitPosition(wk_rev, depot_path))
 
+  def testGetCommitPositionForSkia(self):
+    bisect_instance = _GetBisectPerformanceMetricsInstance(DEFAULT_OPTIONS)
+    skia_rev = 'a94d028e0f2c77f159b3dac95eb90c3b4cf48c61'
+    depot_path = os.path.join(bisect_instance.src_cwd, 'third_party', 'skia')
+    # Skia doesn't use commit positions, and GetCommitPosition should
+    # return None for repos that don't use commit positions.
+    self.assertIsNone(source_control.GetCommitPosition(skia_rev, depot_path))
+
   def testUpdateDepsContent(self):
     bisect_instance = _GetBisectPerformanceMetricsInstance(DEFAULT_OPTIONS)
     deps_file = 'DEPS'
     # We are intentionally reading DEPS file contents instead of string literal
     # with few lines from DEPS because to check if the format we are expecting
     # to search is not changed in DEPS content.
     # TODO (prasadv): Add a separate test to validate the DEPS contents with the
     # format that bisect script expects.
     deps_contents = bisect_perf_regression.ReadStringFromFile(deps_file)
     deps_key = 'v8_revision'
@@ skipping 187 matching lines @@
          ], (None, 0)),
     ]
     self._SetupRunGitMock(try_cmd)
     bisect_perf_regression._BuilderTryjob(
         git_revision, bot_name, bisect_job_name, patch)
 
 
 if __name__ == '__main__':
   unittest.main()