mac: Roll hermetic toolchain to Xcode 8.3.2.

build/mac/should_use_hermetic_xcode.py

 #!/usr/bin/env python
 # Copyright 2016 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.
 
-"""Prints "1" if Chrome targets should be built with hermetic xcode. Otherwise
-prints "0".
+"""
+Prints "1" if Chrome targets should be built with hermetic Xcode.
+Prints "2" if Chrome targets should be built with hermetic Xcode, but the OS
+version does not meet the minimum requirements of the hermetic version of Xcode.
+Otherwise prints "0".
 
 Usage:
   python should_use_hermetic_xcode.py <target_os>
 """
 
 import os
 import sys
 
+_THIS_DIR_PATH = os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+_BUILD_PATH = os.path.join(_THIS_DIR_PATH, os.pardir)
+sys.path.insert(0, _BUILD_PATH)
+
+import mac_toolchain
+
 
 def _IsCorpMachine():
   return os.path.isdir('/Library/GoogleCorpSupport/')
 
 
 def main():
   allow_corp = sys.argv[1] == 'mac' and _IsCorpMachine()
   if os.environ.get('FORCE_MAC_TOOLCHAIN') or allow_corp:
+    if not mac_toolchain.PlatformMeetsHermeticXcodeRequirements(sys.argv[1]):
+      return "2"
     return "1"
   else:
     return "0"
 
 
 if __name__ == '__main__':
   print main()
   sys.exit(0)