[android] Upstream / sync most of build/android and build/android/pylib.

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."""
 
 from pylib import android_commands
 import optparse
-import os
 import sys
 
 
 def main(argv):
   option_parser = optparse.OptionParser()
   option_parser.add_option('--enable_asserts', dest='set_asserts',
       action='store_true', default=None,
       help='Sets the dalvik.vm.enableassertions property to "all"')
   option_parser.add_option('--disable_asserts', dest='set_asserts',
       action='store_false', default=None,
       help='Removes the dalvik.vm.enableassertions property')
-  options, args = option_parser.parse_args(argv)
+  options, _ = option_parser.parse_args(argv)
 
   commands = android_commands.AndroidCommands()
   if options.set_asserts != None:
     if commands.SetJavaAssertsEnabled(options.set_asserts):
       commands.Reboot(full_reboot=False)
 
 
 if __name__ == '__main__':
   main(sys.argv)