gn: Pass through msan flag.

build/gyp_chromium

 #!/usr/bin/env python
 
 # Copyright (c) 2012 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.
 
 # This script is wrapper for Chromium that adds some support for how GYP
 # is invoked by Chromium beyond what can be done in the gclient hooks.
 
 import glob
@@ skipping 193 matching lines @@
       ('fastbuild', '0', 'symbol_level=2'),
       ('fastbuild', '1', 'symbol_level=1'),
       ('fastbuild', '2', 'symbol_level=0'),
       ('OS', 'ios', 'os="ios"'),
       ('OS', 'android', 'os="android"'),
       ('chromeos', '1', 'os="chromeos"'),
       ('use_aura', '1', 'use_aura=true'),
       ('use_goma', '1', 'use_goma=true'),
       ('asan', '1', 'is_asan=true'),
       ('lsan', '1', 'is_lsan=true'),
+      ('msan', '1', 'is_msan=true'),
       ('tsan', '1', 'is_tsan=true'),
   ]
   for i in remap_cases:
     if i[0] in vars_dict and vars_dict[i[0]] == i[1]:
       gn_args += ' ' + i[2]
 
   # These string arguments get passed directly as GN strings.
   for v in ['android_src', 'windows_sdk_path', 'arm_float_abi']:
     if v in vars_dict:
       gn_args += ' ' + v + '=' + EscapeStringForGN(vars_dict[v])
@@ skipping 199 matching lines @@
   args.extend(
       ['-I' + i for i in additional_include_files(supplemental_includes, args)])
 
   args.extend(['-D', 'gyp_output_dir=' + GetOutputDirectory()])
 
   print 'Updating projects from gyp files...'
   sys.stdout.flush()
 
   # Off we go...
   sys.exit(gyp.main(args))