[Android] Don't use a device blacklist if one isn't provided. (RELAND)

build/android/enable_asserts.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.
 
 """Enables dalvik vm asserts in the android device."""
 
 import argparse
 import sys
@@ skipping 10 matching lines @@
   set_asserts_group = parser.add_mutually_exclusive_group(required=True)
   set_asserts_group.add_argument(
       '--enable_asserts', dest='set_asserts', action='store_true',
       help='Sets the dalvik.vm.enableassertions property to "all"')
   set_asserts_group.add_argument(
       '--disable_asserts', dest='set_asserts', action='store_false',
       help='Removes the dalvik.vm.enableassertions property')
 
   args = parser.parse_args()
 
-  if args.blacklist_file:
-    blacklist = device_blacklist.Blacklist(args.blacklist_file)
-  else:
-    blacklist = None
+  blacklist = (device_blacklist.Blacklist(args.blacklist_file)
+               if args.blacklist_file
+               else None)
 
   # TODO(jbudorick): Accept optional serial number and run only for the
   # specified device when present.
   devices = device_utils.DeviceUtils.parallel(
       device_utils.DeviceUtils.HealthyDevices(blacklist))
 
   def set_java_asserts_and_restart(device):
     if device.SetJavaAsserts(args.set_asserts):
       device.RunShellCommand('stop')
       device.RunShellCommand('start')
 
   devices.pMap(set_java_asserts_and_restart)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())