Enable presubmit pylint in build/android.

build/android/pylib/base/base_test_runner.py

Index: build/android/pylib/base/base_test_runner.py
diff --git a/build/android/pylib/base/base_test_runner.py b/build/android/pylib/base/base_test_runner.py
index 2688a6fbfd9a78e6fe20cce0e71ef52b9be12acf..44a457bffe23ced0e55be56c2930ee17c1d19b27 100644
--- a/build/android/pylib/base/base_test_runner.py
+++ b/build/android/pylib/base/base_test_runner.py
@@ -4,15 +4,10 @@
 
 """Base class for running tests on a single device."""
 
-import contextlib
-import httplib
 import logging
-import os
-import tempfile
 import time
 
 from pylib import android_commands
-from pylib import constants
 from pylib import ports
 from pylib.chrome_test_server_spawner import SpawningServer
 from pylib.forwarder import Forwarder
@@ -181,7 +176,7 @@ class BaseTestRunner(object):
     # well as IsHttpServerConnectable(). spawning_server.Start() should also
     # block until the server is ready.
     # Try 3 times to launch test spawner server.
-    for i in xrange(0, 3):
+    for _ in xrange(0, 3):
       self.test_server_spawner_port = ports.AllocateTestServerPort()
       self._ForwardPorts(
           [(self.test_server_spawner_port, self.test_server_spawner_port)])