mb: Allow overriding the path to the gyp script

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 66 matching lines @@
       subp.add_argument('-m', '--master',
                         help='master name to look up config from')
       subp.add_argument('-c', '--config',
                         help='configuration to analyze')
       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',
                         help='path to goma directory')
+      subp.add_argument('--gyp-script', metavar='PATH',
+                        default=self.PathJoin('build', 'gyp_chromium'),
+                        help='path to gyp script relative to project root '
+                             '(default is %(default)s)')
       subp.add_argument('--android-version-code',
                         help='Sets GN arg android_default_version_code and '
                              'GYP_DEFINE app_manifest_version_code')
       subp.add_argument('--android-version-name',
                         help='Sets GN arg android_default_version_name and '
                              'GYP_DEFINE app_manifest_version_name')
       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('-v', '--verbose', action='store_true',
@@ skipping 1001 matching lines @@
     android_version_code = self.args.android_version_code
     if android_version_code:
       gyp_defines += ' app_manifest_version_code=%s' % android_version_code
 
     android_version_name = self.args.android_version_name
     if android_version_name:
       gyp_defines += ' app_manifest_version_name=%s' % android_version_name
 
     cmd = [
         self.executable,
-        self.PathJoin('build', 'gyp_chromium'),
+        self.args.gyp_script,
         '-G',
         'output_dir=' + output_dir,
     ]
 
     # Ensure that we have an environment that only contains
     # the exact values of the GYP variables we need.
     env = os.environ.copy()
 
     # This is a terrible hack to work around the fact that
     # //tools/clang/scripts/update.py is invoked by GYP and GN but
@@ skipping 347 matching lines @@
   # Then check to see if the arg contains any metacharacters other than
   # double quotes; if it does, quote everything (including the double
   # quotes) for safety.
   if any(a in UNSAFE_FOR_CMD for a in arg):
     arg = ''.join('^' + a if a in ALL_META_CHARS else a for a in arg)
   return arg
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))