Reland r212020: Move Python setup/tear down logic into Forwarder ...

build/android/pylib/host_driven/python_test_sharder.py

 # 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.
 
 """Takes care of sharding the python-drive tests in multiple devices."""
 
 import copy
 import logging
 import multiprocessing
 
@@ skipping 104 matching lines @@
     """
     logging.warning('*' * 80)
     logging.warning('Sharding in ' + str(len(self.attached_devices)) +
                     ' devices.')
     logging.warning('Note that the output is not synchronized.')
     logging.warning('Look for the "Final result" banner in the end.')
     logging.warning('*' * 80)
     final_results = base_test_result.TestRunResults()
     tests_to_run = self.tests
 
-    Forwarder.KillHost()
+    Forwarder.UseMultiprocessing()
 
     for retry in xrange(self.retries):
       logging.warning('Try %d of %d', retry + 1, self.retries)
       self._SetupSharding(self.tests)
       test_runners = self._MakeTestRunners(self.attached_devices)
       logging.warning('Starting...')
       pool = multiprocessing.Pool(len(self.attached_devices),
                                   SetTestsContainer,
                                   [PythonTestSharder.tests_container])
 
@@ skipping 58 matching lines @@
       available_tests: a list of tests which subclass PythonTestBase.
       failed_test_names: a list of failed test names.
 
     Returns:
       A list of test objects which correspond to test names found in
       failed_test_names, or an empty list if there is no correspondence.
     """
     tests_to_retry = [t for t in available_tests
                       if t.qualified_name in failed_test_names]
     return tests_to_retry