Add code to debug difference between adb devices checks.

build/android/device_status_check.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012 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.
 
 """A class to keep track of devices across builds and report state."""
-
+import logging
 import optparse
 import os
 import smtplib
 import sys
 
 from pylib import buildbot_report
 from pylib.android_commands import GetAttachedDevices
 from pylib.cmd_helper import GetCmdOutput
 
 
@@ skipping 33 matching lines @@
 
 def CheckForMissingDevices(options, adb_online_devs):
   """Uses file of previous online devices to detect broken phones.
 
   Args:
     options: out_dir parameter of options argument is used as the base
              directory to load and update the cache file.
     adb_online_devs: A list of serial numbers of the currently visible
                      and online attached devices.
   """
+  # TODO(navabi): remove this once the bug that causes different number
+  # of devices to be detected between calls is fixed.
+  logger = logging.getLogger()
+  logger.setLevel(logging.INFO)
+
   out_dir = os.path.abspath(options.out_dir)
 
   def ReadDeviceList(file_name):
     devices_path = os.path.join(out_dir, file_name)
     devices = []
     try:
       with open(devices_path) as f:
         devices = f.read().splitlines()
     except IOError:
       # Ignore error, file might not exist
@@ skipping 18 matching lines @@
     bot_name = os.environ['BUILDBOT_BUILDERNAME']
     slave_name = os.environ['BUILDBOT_SLAVENAME']
     num_online_devs = len(adb_online_devs)
     subject = 'Devices offline on %s, %s (%d remaining).' % (slave_name,
                                                              bot_name,
                                                              num_online_devs)
     buildbot_report.PrintWarning()
     devices_missing_msg = '%d devices not detected.' % len(missing_devs)
     buildbot_report.PrintSummaryText(devices_missing_msg)
 
+    # TODO(navabi): Debug by printing both output from GetCmdOutput and
+    # GetAttachedDevices to compare results.
     body = '\n'.join(
         ['Current online devices: %s' % adb_online_devs,
          '%s are no longer visible. Were they removed?\n' % missing_devs,
          'SHERIFF: See go/chrome_device_monitor',
          'Cache file: %s\n\n' % last_devices_path,
-         'adb devices: %s' % GetCmdOutput(['adb', 'devices'])])
+         'adb devices: %s' % GetCmdOutput(['adb', 'devices']),
+         'adb devices(GetAttachedDevices): %s' % GetAttachedDevices()])
 
     print body
 
     # Only send email if the first time a particular device goes offline
     last_missing = ReadDeviceList('.last_missing')
     new_missing_devs = set(missing_devs) - set(last_missing)
 
     if new_missing_devs:
       msg_body = '\r\n'.join(
           ['From: %s' % from_address,
@@ skipping 37 matching lines @@
   unique_types = list(set(types))
   unique_builds = list(set(builds))
 
   buildbot_report.PrintMsg('Online devices: %d. Device types %s, builds %s'
                            % (len(devices), unique_types, unique_builds))
   print '\n'.join(reports)
   CheckForMissingDevices(options, devices)
 
 if __name__ == '__main__':
   sys.exit(main())