Headless: do not cancel requests if server wants a certificate

... just tell content to proceed with no certificate instead
of cancelling the request.

Bug: 757181
Change-Id: Ib7db0d5bbbdf73dfd3bad4fb5827519eb8c0dbbd
Reviewed-on: https://chromium-review.googlesource.com/996954
Reviewed-by: Alex Clarke <alexclarke@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548422}
3 files changed