[Android] Prepare build/android/ for catapult+devil.

build/android/emma_coverage_stats_test.py

 #!/usr/bin/python
 # 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.
 
 # pylint: disable=protected-access
 
-import os
-import sys
 import unittest
 from xml.etree import ElementTree
 
 import emma_coverage_stats
-from pylib import constants
+from pylib.constants import host_paths
 
-sys.path.append(os.path.join(
-    constants.DIR_SOURCE_ROOT, 'third_party', 'pymock'))
-import mock  # pylint: disable=import-error
+with host_paths.SysPath(host_paths.PYMOCK_PATH):
+  import mock  # pylint: disable=import-error
 
 EMPTY_COVERAGE_STATS_DICT = {
   'files': {},
   'patch': {
     'incremental': {
       'covered': 0, 'total': 0
     }
   }
 }
 
@@ skipping 528 matching lines @@
   mock_open = mock.mock_open()
   mock_open.side_effect = [mock.mock_open(read_data=side_effect).return_value
                            for side_effect in side_effects]
   with mock.patch('__builtin__.open', mock_open):
     return func(**kwargs), mock_open
 
 
 if __name__ == '__main__':
   # Suppress logging messages.
   unittest.main(buffer=True)