Log the GN args again in `mb gen`.

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 704 matching lines @@
   def RunGNGen(self, vals):
     build_dir = self.args.path[0]
 
     cmd = self.GNCmd('gen', build_dir, '--check')
     gn_args = self.GNArgs(vals)
 
     # Since GN hasn't run yet, the build directory may not even exist.
     self.MaybeMakeDirectory(self.ToAbsPath(build_dir))
 
     gn_args_path = self.ToAbsPath(build_dir, 'args.gn')
-    self.WriteFile(gn_args_path, gn_args)
+    self.WriteFile(gn_args_path, gn_args, force_verbose=True)
 
     swarming_targets = []
     if getattr(self.args, 'swarming_targets_file', None):
       # We need GN to generate the list of runtime dependencies for
       # the compile targets listed (one per line) in the file so
       # we can run them via swarming. We use ninja_to_gn.pyl to convert
       # the compile targets to the matching GN labels.
       path = self.args.swarming_targets_file
       if not self.Exists(path):
         self.WriteFailureAndRaise('"%s" does not exist' % path,
@@ skipping 676 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:]))