[Android] Add a configurable environment for devil/.

build/android/devil/android/sdk/shared_prefs_test.py

Index: build/android/devil/android/sdk/shared_prefs_test.py
diff --git a/build/android/devil/android/sdk/shared_prefs_test.py b/build/android/devil/android/sdk/shared_prefs_test.py
index 63d9aeceea6bb149f5c290910953d658fa852bc2..7623f6c35d4bc3156f0467c3b4c657e23cd08bb6 100755
--- a/build/android/devil/android/sdk/shared_prefs_test.py
+++ b/build/android/devil/android/sdk/shared_prefs_test.py
@@ -8,16 +8,14 @@ Unit tests for the contents of shared_prefs.py (mostly SharedPrefs).
 """
 
 import logging
-import os
 import sys
 import unittest
 
+from devil import devil_env
 from devil.android import device_utils
 from devil.android.sdk import shared_prefs
-from pylib import constants
 
-sys.path.append(os.path.join(
-    constants.DIR_SOURCE_ROOT, 'third_party', 'pymock'))
+sys.path.append(devil_env.config.pymock_path)
 import mock # pylint: disable=import-error