telemetry_AFDOGenerate: fix missing comma in a tuple.

BUG=chromium:1045159
TEST=Tested option by hand and it worked.

Change-Id: Iefef354f3540efe5fb3e9b387620f2fc5956370a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2033486
Tested-by: Luis Lozano <llozano@chromium.org>
Auto-Submit: Luis Lozano <llozano@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Caroline Tice <cmtice@chromium.org>
Commit-Queue: Manoj Gupta <manojgupta@chromium.org>
Commit-Queue: Luis Lozano <llozano@chromium.org>
diff --git a/server/site_tests/telemetry_AFDOGenerate/telemetry_AFDOGenerate.py b/server/site_tests/telemetry_AFDOGenerate/telemetry_AFDOGenerate.py
index 3a83b1b..a006e0c 100644
--- a/server/site_tests/telemetry_AFDOGenerate/telemetry_AFDOGenerate.py
+++ b/server/site_tests/telemetry_AFDOGenerate/telemetry_AFDOGenerate.py
@@ -88,9 +88,9 @@
          ('--story-tag-filter=tough_canvas',
           '--story-filter="bouncing\\*\\|canvas\\*\\|microsoft\\*"',
           '--legacy-json-trace-format')),
-        ('octane', ('--legacy-json-trace-format')),
-        ('kraken', ('--legacy-json-trace-format')),
-        ('speedometer2', ('--legacy-json-trace-format')),
+        ('octane', ('--legacy-json-trace-format',)),
+        ('kraken', ('--legacy-json-trace-format',)),
+        ('speedometer2', ('--legacy-json-trace-format',)),
 )
 
 # Temporarily disable this benchmark because it is failing a