Support 'never' as expiry date.

Bug: 923083
Change-Id: I25136857b84832ac896e76f32c182af8eb190e15
Reviewed-on: https://chromium-review.googlesource.com/c/1418517
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625353}
2 files changed