[devil refactor] Prepare clients for DeviceUnreachableError

build/android/tombstones.py

 #!/usr/bin/env python
 #
 # 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.
 #
 # Find the most recent tombstone file(s) on all connected devices
 # and prints their stacks.
 #
 # Assumes tombstone file was created with current symbols.
@@ skipping 31 matching lines @@
   try:
     if not device.PathExists('/data/tombstones', as_root=True):
       return
     entries = device.StatDirectory('/data/tombstones', as_root=True)
     for entry in entries:
       if 'tombstone' in entry['filename']:
         yield (entry['filename'],
                datetime.datetime.fromtimestamp(entry['st_mtime']))
   except device_errors.CommandFailedError:
     logging.exception('Could not retrieve tombstones.')
+  except device_errors.DeviceUnreachableError:
+    logging.exception('Device unreachable retrieving tombstones.')
   except device_errors.CommandTimeoutError:
     logging.exception('Timed out retrieving tombstones.')
 
 
 def _GetDeviceDateTime(device):
   """Determine the date time on the device.
 
   Args:
     device: An instance of DeviceUtils.
 
@@ skipping 242 matching lines @@
   for device in devices:
     resolved_tombstones = ResolveTombstones(
         device, args.all_tombstones,
         args.stack, args.wipe_tombstones, args.jobs)
     for line in resolved_tombstones:
       logging.info(line)
 
 
 if __name__ == '__main__':
   sys.exit(main())