[Android] Move base tests classes to pylib/base

build/android/pylib/sharded_tests_queue.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.
-
-
-"""A module that contains a queue for running sharded tests."""
-
-import multiprocessing
-
-
-class ShardedTestsQueue(object):
-  """A queue for managing pending tests across different runners.
-
-  This class should only be used when sharding.
-
-  Attributes:
-    num_devices: an integer; the number of attached Android devices.
-    tests: a list of tests to be run.
-    tests_queue: if sharding, a JoinableQueue object that holds tests from
-        |tests|. Otherwise, a list holding tests.
-    results_queue: a Queue object to hold TestResults objects.
-  """
-  _STOP_SENTINEL = 'STOP'  # sentinel value for iter()
-
-  def __init__(self, num_devices, tests):
-    self.num_devices = num_devices
-    self.tests_queue = multiprocessing.Queue()
-    for test in tests:
-      self.tests_queue.put(test)
-    for _ in xrange(self.num_devices):
-      self.tests_queue.put(ShardedTestsQueue._STOP_SENTINEL)
-
-  def __iter__(self):
-    """Returns an iterator with the test cases."""
-    return iter(self.tests_queue.get, ShardedTestsQueue._STOP_SENTINEL)