Fix additional merge script args

They currently aren't being parsed correctly, due to the additional args
looking like command line arguments the merge_results.py script wants to
process. This changes it to require a JSON serialized array of strings,
which won't be consumed by the parser.

We can't use nargs='*' because we already use that to receive the list
of input test results.

Bug: 923711
Change-Id: I5709ffdcdce653e8f46b4ef6c3b8ae2cc9579127
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1572805
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Auto-Submit: Stephen Martinis <martiniss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653237}
1 file changed