Change gtest launcher to run in parallel and retry failures by default.

tools/telemetry/telemetry/unittest/run_tests.py

 # Copyright 2012 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.
 
 import logging
 import unittest
 
 from telemetry import decorators
 from telemetry.core import browser_finder
 from telemetry.core import browser_options
@@ skipping 108 matching lines @@
     return parser
 
   @classmethod
   def AddCommandLineArgs(cls, parser):
     parser.add_option('--repeat-count', type='int', default=1,
                       help='Repeats each a provided number of times.')
     parser.add_option('-d', '--also-run-disabled-tests',
                       dest='run_disabled_tests',
                       action='store_true', default=False,
                       help='Ignore @Disabled and @Enabled restrictions.')
-    parser.add_option('--retry-limit', type='int', default=0,
-                      help='Retry each failure up to N times (default %default)'
+    parser.add_option('--retry-limit', type='int',
+                      help='Retry each failure up to N times'
                            ' to de-flake things.')
     json_results.AddOptions(parser)
 
   @classmethod
   def ProcessCommandLineArgs(cls, parser, args):
     if args.verbosity == 0:
       logging.getLogger().setLevel(logging.WARN)
 
+    # We retry failures by default unless we're running a list of tests
+    # explicitly.
+    if args.retry_limit is None and not args.positional_args:
+      args.retry_limit = 3
+
     try:
       possible_browser = browser_finder.FindBrowser(args)
     except browser_finder.BrowserFinderException, ex:
       parser.error(ex)
 
     if not possible_browser:
       parser.error('No browser found of type %s. Cannot run tests.\n'
                    'Re-run with --browser=list to see '
                    'available browser types.' % args.browser_type)
 
@@ skipping 36 matching lines @@
                                args.run_disabled_tests)
     runner = progress_reporter.TestRunner()
     result = runner.run(test_suite, config.progress_reporters,
                         args.repeat_count, args)
     return test_suite, result
 
   @classmethod
   @RestoreLoggingLevel
   def main(cls, args=None):
     return super(RunTestsCommand, cls).main(args)