Update from https://crrev.com/304121

tools/clang/scripts/test_tool.py

 #!/usr/bin/env python
 # Copyright (c) 2013 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.
 
 """Test harness for chromium clang tools."""
 
 import difflib
 import glob
 import json
 import os
 import os.path
 import subprocess
 import shutil
 import sys
 
 
 def _GenerateCompileCommands(files, include_paths):
   """Returns a JSON string containing a compilation database for the input."""
   include_path_flags = ' '.join('-I %s' % include_path
                                for include_path in include_paths)
   return json.dumps([{'directory': '.',
-                      'command': 'clang++ -fsyntax-only %s -c %s' % (
+                      'command': 'clang++ -std=c++11 -fsyntax-only %s -c %s' % (
                           include_path_flags, f),
                       'file': f} for f in files], indent=2)
 
 
 def _NumberOfTestsToString(tests):
   """Returns an English describing the number of tests."""
   return "%d test%s" % (tests, 's' if tests != 1 else '')
 
 
 def main(argv):
@@ skipping 83 matching lines @@
   finally:
     # No matter what, unstage the git changes we made earlier to avoid polluting
     # the index.
     args = ['git', 'reset', '--quiet', 'HEAD']
     args.extend(actual_files)
     subprocess.call(args)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))