GitLab

If the server doesn't support partial responses, Chrome should cancel
parallel download requests.
These requests result in the wrong write offset and makes the file larger
than the original

BUG=838627

Change-Id: I1fa878854579a1572e6e2f90f3bb932b59b333ba
Reviewed-on: https://chromium-review.googlesource.com/1048130
Commit-Queue: Min Qin <qinmin@chromium.org>
Reviewed-by: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557252}