Add option to specify ADB binary in test runner.

build/android/pylib/device/adb_wrapper.py

 # Copyright 2013 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.
 
 """This module wraps Android's adb tool.
 
 This is a thin wrapper around the adb interface. Any additional complexity
 should be delegated to a higher level (ex. DeviceUtils).
 """
 
 import errno
 import os
 
 from pylib import cmd_helper
+from pylib import constants
 from pylib.device import decorators
 from pylib.device import device_errors
 from pylib.utils import timeout_retry
 
 
 _DEFAULT_TIMEOUT = 30
 _DEFAULT_RETRIES = 2
 
 
 def _VerifyLocalFileExists(path):
@@ skipping 17 matching lines @@
 
     Args:
       device_serial: The device serial number as a string.
     """
     self._device_serial = str(device_serial)
 
   # pylint: disable=unused-argument
   @classmethod
   @decorators.WithTimeoutAndRetries
   def _RunAdbCmd(cls, arg_list, timeout=None, retries=None, check_error=True):
-    cmd = ['adb'] + arg_list
+    cmd = [constants.GetAdbPath()] + arg_list
     exit_code, output = cmd_helper.GetCmdStatusAndOutputWithTimeout(
       cmd, timeout_retry.CurrentTimeoutThread().GetRemainingTime())
     if exit_code != 0:
       raise device_errors.AdbCommandFailedError(
           cmd, 'returned non-zero exit code %d and output %r' %
           (exit_code, output))
     # This catches some errors, including when the device drops offline;
     # unfortunately adb is very inconsistent with error reporting so many
     # command failures present differently.
     if check_error and output[:len('error:')] == 'error:':
@@ skipping 326 matching lines @@
     """Restarts the adbd daemon with root permissions, if possible.
 
     Args:
       timeout: (optional) Timeout per try in seconds.
       retries: (optional) Number of retries to attempt.
     """
     output = self._DeviceAdbCmd(['root'], timeout, retries)
     if 'cannot' in output:
       raise device_errors.AdbCommandFailedError(['root'], output)