Update docs and command line flags for MB.

tools/mb/mb.py

Index: tools/mb/mb.py
diff --git a/tools/mb/mb.py b/tools/mb/mb.py
index 501cc56117c26b92eb2beb547886a0e50f8b5b18..cc66b1b7e09b04c21141037cee5ab17ebd0ea232 100755
--- a/tools/mb/mb.py
+++ b/tools/mb/mb.py
@@ -65,8 +65,8 @@ class MetaBuildWrapper(object):
                         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, '

[M-A Ruel, 2015/06/25 13:31:13]

Why add () ?

[Dirk Pranke, 2015/06/25 16:06:15]

Habit, I think :). Will remove.

+                              'just return an exit code.'))
       subp.add_argument('-v', '--verbose', action='count',
                         help='verbose logging (may specify multiple times).')
 
@@ -77,9 +77,6 @@ class MetaBuildWrapper(object):
                             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,
@@ -108,7 +105,13 @@ class MetaBuildWrapper(object):
 
     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',