Grant legacy cookie access semantics if last eligible access was recent

This implements behind a default disabled base::Feature a mechanism by
which cookies that were accessed recently enough (as specified by a
FeatureParam value) from an eligible context are granted legacy cookie
access semantics. A previous cookie access is considered eligible if it
allowed HttpOnly cookies, and was same-site (strictly for get, laxly
for set).

Bug: 1029099
Change-Id: Id7bea1ca37e2d1d97a4c8c836f07758c8e647e05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1948233
Reviewed-by: Maksim Orlovich <[email protected]>
Commit-Queue: Lily Chen <[email protected]>
Cr-Commit-Position: refs/heads/master@{#721254}
8 files changed