Update docs and command line flags for MB.

tools/mb/mb.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 """MB - the Meta-Build wrapper around GYP and GN
 
 MB is a wrapper script for GYP and GN that can be used to generate build files
 for sets of canned configurations and analyze them.
 """
@@ skipping 47 matching lines @@
       subp.add_argument('-f', '--config-file', metavar='PATH',
                         default=self.default_config,
                         help='path to config file '
                             '(default is //tools/mb/mb_config.pyl)')
       subp.add_argument('-g', '--goma-dir', default=self.ExpandUser('~/goma'),
                         help='path to goma directory (default is %(default)s).')
       subp.add_argument('-n', '--dryrun', action='store_true',
                         help='Do a dry run (i.e., do nothing, just print '
                              'the commands that will run)')
       subp.add_argument('-q', '--quiet', action='store_true',
-                        help='Do not print anything, just return an exit '
-                             'code.')
+                        help='Do not print anything on success, '
+                             'just return an exit code.')
       subp.add_argument('-v', '--verbose', action='count',
                         help='verbose logging (may specify multiple times).')
 
     parser = argparse.ArgumentParser(prog='mb')
     subps = parser.add_subparsers()
 
     subp = subps.add_parser('analyze',
                             help='analyze whether changes to a set of files '
                                  'will cause a set of binaries to be rebuilt.')
     AddCommonOptions(subp)
-    subp.add_argument('--swarming-targets-file',
-                      help='save runtime dependencies for targets listed '
-                           'in file.')
     subp.add_argument('path', nargs=1,
                       help='path build was generated into.')
     subp.add_argument('input_path', nargs=1,
                       help='path to a file containing the input arguments '
                            'as a JSON object.')
     subp.add_argument('output_path', nargs=1,
                       help='path to a file containing the output arguments '
                            'as a JSON object.')
     subp.set_defaults(func=self.CmdAnalyze)
 
     subp = subps.add_parser('gen',
                             help='generate a new set of build files')
     AddCommonOptions(subp)
     subp.add_argument('--swarming-targets-file',
                       help='save runtime dependencies for targets listed '
                            'in file.')
     subp.add_argument('path', nargs=1,
                       help='path to generate build into')
     subp.set_defaults(func=self.CmdGen)
 
     subp = subps.add_parser('lookup',
                             help='look up the command for a given config or '
                                  'builder')
     AddCommonOptions(subp)
     subp.set_defaults(func=self.CmdLookup)
 
     subp = subps.add_parser('validate',
                             help='validate the config file')
-    AddCommonOptions(subp)
+    subp.add_argument('-f', '--config-file', metavar='PATH',
+                      default=self.default_config,
+                      help='path to config file '
+                          '(default is //tools/mb/mb_config.pyl)')
+    subp.add_argument('-q', '--quiet', action='store_true',
+                      help='Do not print anything on success, '
+                           'just return an exit code.')
     subp.set_defaults(func=self.CmdValidate)
 
     subp = subps.add_parser('help',
                             help='Get help on a subcommand.')
     subp.add_argument(nargs='?', action='store', dest='subcommand',
                       help='The command to get help for.')
     subp.set_defaults(func=self.CmdHelp)
 
     self.args = parser.parse_args(argv)
 
@@ skipping 610 matching lines @@
 
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv[1:]))
   except MBErr as e:
     print(e)
     sys.exit(1)
   except KeyboardInterrupt:
     print("interrupted, exiting", stream=sys.stderr)
     sys.exit(130)