Log what devices were read from the target devices file.

build/android/pylib/local/device/local_device_environment.py

 # Copyright 2014 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.
 
 import datetime
 import logging
 import os
 import shutil
 import tempfile
 import threading
@@ skipping 37 matching lines @@
   #override
   def SetUp(self):
     device_arg = 'default'
     if self._target_devices_file:
       device_arg = device_list.GetPersistentDeviceList(
           self._target_devices_file)
       if not device_arg:
         logging.warning('No target devices specified. Falling back to '
                         'running on all available devices.')
         device_arg = 'default'
+      else:
+        logging.info(
+            'Read device list %s from target devices file.', str(device_arg))
     elif self._device_serial:
       device_arg = self._device_serial
 
     self._devices = device_utils.DeviceUtils.HealthyDevices(
         self._blacklist, enable_device_files_cache=self._enable_device_cache,
         default_retries=self._max_tries - 1, device_arg=device_arg)
     if not self._devices:
       raise device_errors.NoDevicesError
 
     if self._enable_device_cache:
@@ skipping 63 matching lines @@
           [m.output_file for m in self._logcat_monitors])
       shutil.rmtree(self._logcat_output_dir)
 
   def BlacklistDevice(self, device, reason='local_device_failure'):
     device_serial = device.adb.GetDeviceSerial()
     if self._blacklist:
       self._blacklist.Extend([device_serial], reason=reason)
     with self._devices_lock:
       self._devices = [d for d in self._devices if str(d) != device_serial]