Network Service: Make CanonicalCookie times non-nullable.

base::Time already has a null value, so adding mojo's nullable type
support on top of base::Time is more confusing than useful.

Bug: 729800
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: I6016a46b48b4efc4e9b584bc5c3062849dab60a0
Reviewed-on: https://chromium-review.googlesource.com/1087539
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564962}
4 files changed