MB: Run test with gtest-parallel on swarming.

third_party/gtest-parallel/gtest-parallel

Index: third_party/gtest-parallel/gtest-parallel
diff --git a/third_party/gtest-parallel/gtest-parallel b/third_party/gtest-parallel/gtest-parallel
index 4e80928df659269eca75f169dbefc2f545c83025..10e7452b4dd39ca219c089b9120ec71f89388d08 100755
--- a/third_party/gtest-parallel/gtest-parallel
+++ b/third_party/gtest-parallel/gtest-parallel
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright 2013 Google Inc. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -321,6 +321,11 @@ for test_binary in binaries:
     tests.append((times.get_test_time(test_binary, test),
                   test_binary, test, command))
 
+shard_count = int(os.environ.get('GTEST_TOTAL_SHARDS', 1))

[kjellander_webrtc, 2016/11/15 15:13:36]

Since this is both ugly and hard to know, could we add two flags instead, where
the default values are the environment variable's values, with fallback on 1 and
0?

Like:
parser.add_option('--shard-count', type='int',
  default=int(os.environ.get('GTEST_TOTAL_SHARDS', 1)),
  help='Total number of shards (for sharding test execution between multiple
machines). Default: %default')
parser.add_option('--shard-run', type='int',
  default=int(os.environ.get('GTEST_SHARD_INDEX', 0)),
  help='Zero-indexed number identifying this shard  (for sharding test execution
between multiple machines). Default: %default')

Then use these flags here instead.

+shard_run = int(os.environ.get('GTEST_SHARD_INDEX', 0))
+
+tests = tests[shard_run::shard_count]
+
 if options.failed:
   # The first element of each entry is the runtime of the most recent
   # run if it was successful, or None if the test is new or the most