[autotest] Add old RPC support to test_that

BUG=chromium:763207
TEST=trybot
TEST=test_that :lab: -b reks -i reks-release/R63-9927.0.0 -p suites dummy_Pass -w cautotest
TEST=Run test_that against old moblab (verify bug fix)

Change-Id: I18ee13e8b561b0595358aba4f5cb3e8cb148c140
Reviewed-on: https://chromium-review.googlesource.com/661218
Commit-Ready: Allen Li <ayatane@chromium.org>
Tested-by: Allen Li <ayatane@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Laurence Goodby <lgoodby@chromium.org>
diff --git a/site_utils/test_that.py b/site_utils/test_that.py
index f454b44..7804392 100755
--- a/site_utils/test_that.py
+++ b/site_utils/test_that.py
@@ -163,6 +163,10 @@
     parser.add_argument('-x', '--max_runtime_mins', type=int,
                         dest='max_runtime_mins', default=20,
                         help='Default time allowed for the tests to complete.')
+    # TODO(crbug.com/763207): This is to support calling old moblab RPC
+    # with ToT code.  This does not need to be supported after M62.
+    parser.add_argument('--oldrpc', action='store_true',
+                        help='Use old AFE RPC.')
     _, remaining_argv = parser.parse_known_args(argv)
     return parser, remaining_argv
 
@@ -315,6 +319,10 @@
                '--max_runtime_mins=%s' % str(arguments.max_runtime_mins),
                '--suite_args=%s'
                % repr({'tests': _suite_arg_tests(argv)})]
+    # TODO(crbug.com/763207): This is to support calling old moblab RPC
+    # with ToT code.  This does not need to be supported after M62.
+    if arguments.oldrpc:
+        command.append('--oldrpc')
     if arguments.web:
         command.extend(['--web=%s' % (arguments.web,)])
     logging.info('About to start lab suite with command %s.', command)