Add --retry_failed=3 flag to gtest-parallel.

tools-webrtc/mb/mb.py

 #!/usr/bin/env python
 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 """MB - the Meta-Build wrapper around GYP and GN
@@ skipping 1084 matching lines @@
         sep = '\\' if self.platform == 'win32' else '/'
         output_dir = '${ISOLATED_OUTDIR}' + sep + 'test_logs'
         gtest_parallel_wrapper = [
             '../../tools-webrtc/gtest-parallel-wrapper.py',
             '--output_dir=%s' % output_dir,
             '--gtest_color=no',
             # We tell gtest-parallel to interrupt the test after 900 seconds,
             # so it can exit cleanly and report results, instead of being
             # interrupted by swarming and not reporting anything.
             '--timeout=900',
+            '--retry_failed=3',
         ]
 
       asan = 'is_asan=true' in vals['gn_args']
       msan = 'is_msan=true' in vals['gn_args']
       tsan = 'is_tsan=true' in vals['gn_args']
 
       executable_prefix = '.\\' if self.platform == 'win32' else './'
       executable_suffix = '.exe' if self.platform == 'win32' else ''
       executable = executable_prefix + target + executable_suffix
 
@@ skipping 421 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:]))