[Fuchsia] Enable TestLauncher bot-mode for all test-suite runs.

Add pass-through for --test-launcher-bot-mode and set it via mb.py for
all non-script steps that we run on Fuchsia.  The main difference this
makes is to enable the TestLauncher's default bot-mode retry-limit.

Bug: 911160
Change-Id: I036c0d466c37dfdcd64c7faebdfc7d25ee6a00a5
Reviewed-on: https://chromium-review.googlesource.com/c/1358636
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613360}

build/fuchsia/test_runner.py

@@ -63,12 +63,18 @@ def main():
                       help='Enable Chrome test server spawner.')
   parser.add_argument('child_args', nargs='*',
                       help='Arguments for the test process.')
+  parser.add_argument('--test-launcher-bot-mode', action='store_true',
+                      default=False,
+                      help='Informs the TestLauncher to that it should enable '
+                      'special allowances for running on a test bot.')
   args = parser.parse_args()
   ConfigureLogging(args)
 
   child_args = ['--test-launcher-retry-limit=0']
   if args.single_process_tests:
     child_args.append('--single-process-tests')
+  if args.test_launcher_bot_mode:
+    child_args.append('--test-launcher-bot-mode')
   if args.test_launcher_batch_limit:
     child_args.append('--test-launcher-batch-limit=%d' %
                        args.test_launcher_batch_limit)

tools/mb/mb.py

@@ -1112,6 +1112,7 @@ class MetaBuildWrapper(object):
       cmdline = [
           '../../testing/test_env.py',
           os.path.join('bin', 'run_%s' % target),
+          '--test-launcher-bot-mode',
       ]
     elif is_simplechrome and test_type != 'script':
       cmdline = [