GitLab

Added warning and exit when attempting to use the single_process
flag to run the tests and launcher in a single process.


Bug: 460513
Change-Id: I344f4477580ed81490002cd13ef5f5e4ed7a021d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894757Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Thomas Lukaszewicz <tluk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711862}