Enable some profile_chrome unit tests on Trybots

systrace/bin/run_tests

 #!/usr/bin/env python2.7
 
 # Copyright 2015 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.
 
 """Runs the unit test suite for systrace."""
 
 import optparse
 import os
 import sys
 import unittest
 
 _SYSTRACE_DIR = os.path.abspath(
     os.path.join(os.path.dirname(__file__), os.path.pardir))
 sys.path.insert(0, _SYSTRACE_DIR)
 from systrace import decorators
 
 
 def main():
   parser = optparse.OptionParser()
   parser.add_option("-d", "--device", dest="device",
                     help="device the test runs on", metavar="DEVICE")
   options, _args = parser.parse_args()  # pylint: disable=unused-variable
-  systrace_package_path = os.path.join(_SYSTRACE_DIR, 'systrace')
   unfiltered_suite = unittest.TestLoader().discover(
-      systrace_package_path,
+      _SYSTRACE_DIR,
       pattern = '*_unittest.py',
       top_level_dir=_SYSTRACE_DIR)
   suite = unittest.TestSuite()
 
   for test_group in unfiltered_suite._tests:
     for inner_group in test_group:
       for test in inner_group:
         method = getattr(
           test, test._testMethodName)  # pylint: disable=protected-access
         if not decorators.ShouldSkip(method, options.device):
           suite.addTest(test)
 
   result = unittest.TextTestRunner(verbosity=2).run(suite)
   if result.wasSuccessful():
     sys.exit(0)
   else:
     sys.exit(1)
 
 if __name__ == '__main__':
   main()