Make it possible to shard run_tool.py invocations.

BUG=578344
R=danakj@chromium.org

Review-Url: https://codereview.chromium.org/2805893003 .
Cr-Original-Commit-Position: refs/heads/master@{#462974}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 8dcf8d7130873385e61338446a377e76966545a2
1 file changed