Add option to allow mojob to specify extra gn args.

mojo/tools/mojob.py

Index: mojo/tools/mojob.py
diff --git a/mojo/tools/mojob.py b/mojo/tools/mojob.py
index 7f60900656af4c6251c0fde73c841b9bdae25b0c..498004ffdc8f8bd18aa26eddc7d7b4d8c26ae840 100755
--- a/mojo/tools/mojob.py
+++ b/mojo/tools/mojob.py
@@ -64,6 +64,11 @@ def _args_to_config(args):
   if 'test_results_server' in args:
     additional_args['test_results_server'] = args.test_results_server
 
+  if 'extra_args' in args and args.extra_args:
+    for arg in args.extra_args.split(' '):
+      (name, val) = arg.split('=')
+      additional_args[name] = val
+
   return Config(target_os=target_os, target_cpu=target_cpu,
                 is_debug=args.debug, dcheck_always_on=args.dcheck_always_on,
                 **additional_args)
@@ -215,6 +220,8 @@ def main():
   gn_parser = subparsers.add_parser('gn', parents=[parent_parser],
                                     help='Run gn for mojo (does not sync).')
   gn_parser.set_defaults(func=gn)
+  gn_parser.add_argument('--args', help='Specify extra args for gn phase',

[qsr, 2015/03/09 11:58:41]

No need to specify that it is for the gn phase. This parser is only for the gn
phase, so won't be used for anything else.

[haltonhuo, 2015/03/09 12:13:00]

It is added only under "gn" sub-command, did I missing something?

[qsr, 2015/03/09 13:13:06]

 I meant that you do not need to speak about the gn phasein the help message.
Just have 'Specify extra args'

[haltonhuo, 2015/03/10 06:50:43]

Done in patch set 6.

+                         default=None, dest='extra_args')
   clang_group = gn_parser.add_mutually_exclusive_group()
   clang_group.add_argument('--clang', help='Use Clang (default)', default=None,
                            action='store_true')