Removing extra comma

Bug: 757933
Change-Id: Iaa6e4d2e254dccef2f6e4a81909b3eefa7f7fd46
Reviewed-on: https://chromium-review.googlesource.com/969954
Commit-Queue: Emily Hanley <eyaich@chromium.org>
Reviewed-by: Emily Hanley <eyaich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544339}

tools/perf/process_perf_results.py

@@ -24,7 +24,7 @@ def _upload_perf_results(json_to_upload, name, configuration_name,
   build_properties = json.loads(build_properties)
   if not configuration_name:
     # we are deprecating perf-id crbug.com/817823
-    configuration_name = build_properties['buildername'],
+    configuration_name = build_properties['buildername']
   args = [
       '--tmp-dir', tmp_dir,
       '--buildername', build_properties['buildername'],