GitLab

Adds new tests for Schemeful Same-Site along with a virtual test suite
which enables the SchemefulSameSite feature.

Because Schemeful Same-Site only modifies the definition of "same-site"
it's adequate to test only a few cases that confirm the expected
same-siteness rather than try to thoroughly test all possible
`SameSite` situations.


Bug: 1127348
Change-Id: I9b914dd425bfb8cda6fc1ddc9f3606940f0b9a1d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2412907
Commit-Queue: Steven Bingler <bingler@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807923}