Don't display colors on gtest-parallel logs on swarming.

It makes the logs hard to read, and swarming doesn't output colors anyway.

Also:
- Fix a bug where we tried to access output_dir when combining the logs even if the flag was not set.
- Update a comment explaining why we just 'eat' the --isolated-script-test-chartjson-output flag.

NOTRY=True
BUG=webrtc:7524

Review-Url: https://codereview.webrtc.org/2843263005
Cr-Commit-Position: refs/heads/master@{#17973}

tools-webrtc/gtest-parallel-wrapper.py

@@ -61,10 +61,15 @@ def main():
   parser = argparse.ArgumentParser()
   parser.add_argument('--isolated-script-test-output', type=str, default=None)
 
-  # TODO(ehmaldonado): Implement this flag instead of just "eating" it.
+  # We don't need to implement this flag, and possibly can't, since it's
+  # intended for results of Telemetry tests. See
+  # https://chromium.googlesource.com/external/github.com/catapult-project/catapult/+/HEAD/dashboard/docs/data-format.md
   parser.add_argument('--isolated-script-test-chartjson-output', type=str,
                       default=None)
 
+  # TODO(ehmaldonado): Figure out a way to avoid duplicating the flags in
+  # gtest-parallel.
+  parser.add_argument('--gtest_color', type=str, default='auto')
   parser.add_argument('--output_dir', type=str, default=None)
   parser.add_argument('--timeout', type=int, default=None)
 
@@ -89,6 +94,8 @@ def main():
       gtest_total_shards,
       '--shard_index',
       gtest_shard_index,
+      '--gtest_color',
+      options.gtest_color,
   ]
 
   # --isolated-script-test-output is used to upload results to the flakiness
@@ -122,6 +129,7 @@ def main():
 
   exit_code = subprocess.call(command, env=test_env, cwd=os.getcwd())
 
+  if options.output_dir:
     for test_status in 'passed', 'failed', 'interrupted':
       logs_dir = os.path.join(options.output_dir, test_status)
       if not os.path.isdir(logs_dir):

tools-webrtc/mb/mb.py

@@ -1096,6 +1096,7 @@ class MetaBuildWrapper(object):
         output_dir = '${ISOLATED_OUTDIR}' + sep + 'test_logs'
         gtest_parallel_wrapper = [
             '../../tools-webrtc/gtest-parallel-wrapper.py',
+            '--gtest_color=no',
             '--output_dir=%s' % output_dir,
         ]
 

tools-webrtc/mb/mb_unittest.py

@@ -448,6 +448,7 @@ class UnitTest(unittest.TestCase):
     self.assertEqual(command, [
         '../../testing/test_env.py',
         '../../tools-webrtc/gtest-parallel-wrapper.py',
+        '--gtest_color=no',
         '--output_dir=${ISOLATED_OUTDIR}/test_logs',
         './base_unittests',
         '--workers=1',
@@ -493,6 +494,7 @@ class UnitTest(unittest.TestCase):
     self.assertEqual(command, [
         '../../testing/xvfb.py',
         '../../tools-webrtc/gtest-parallel-wrapper.py',
+        '--gtest_color=no',
         '--output_dir=${ISOLATED_OUTDIR}/test_logs',
         './base_unittests',
         '--',
@@ -538,6 +540,7 @@ class UnitTest(unittest.TestCase):
     self.assertEqual(command, [
         '../../testing/test_env.py',
         '../../tools-webrtc/gtest-parallel-wrapper.py',
+        '--gtest_color=no',
         '--output_dir=${ISOLATED_OUTDIR}\\test_logs',
         r'.\unittests.exe',
         '--',
@@ -579,6 +582,7 @@ class UnitTest(unittest.TestCase):
     self.assertEqual(command, [
         '../../testing/test_env.py',
         '../../tools-webrtc/gtest-parallel-wrapper.py',
+        '--gtest_color=no',
         '--output_dir=${ISOLATED_OUTDIR}/test_logs',
         './base_unittests',
         '--',