Making cookies eviction quotas match spec

According to the section 3 and section 5 in
https://tools.ietf.org/html/draft-west-cookie-priority-
00#section-3, the old cookie monster implementation doesn't
maintain priority quotas correctly.

This CL makes sure there will always be at least 30 low
priority cookies, 50 mid priority and 70 high priority
cookies if there had been enough of them before  the eviction.
Please note, secure cookies are more important than non-secure
per https://tools.ietf.org/html/draft-west-leave-secure-cookies-alone.

A small example: if there are 70 cookies:
37 non-secure low priority and 33 secure low priority
cookies, 37 non-secure cookies are deleted during the first
round and other 3 secure low priority cookies are deleted
during the following round preserving 30 low priority
cookies according to the quota of those specific cookies.
For a bigger example that fully complies with the
implementation, check the unittests.

Before the fix, the unittests were just adjusted to the
behavior of cookies eviction.

For example, if we take the following unittest:
Round 1 => 10L; round 2 => 11M, 10L; round 3 => none.
TestPriorityCookieCase(cm.get(), "11HN 10MN 20LN 110MN 20LN
10HN", 20U,109U, 21U, 150U, 0U);
The problem here was that there were only 40 low priority
cookies, but the quota was not preserved for those cookies.
First, 10 low priority cookies were deleted and then more 10
low priority cookies were deleted leaving only 20 of them,
which was less than the quota (30 low priority cookies).
It happened because the eviction algorithm didn't know how
many cookies of a specific priority were deleted and
it had always started to delete all the cookies from the
beginning of the container removing even those cookies
that shouldn't have been deleted.

After we land this CL, we can have cookies in any order and
high priority cookies will be eventually deleted in order
to avoid excess of high priority cookies by some
applications within the same domain. Thus, after the
eviction algorithm runs, we should have at least 30 low, 50
mid and 70 high priority cookies if we had sufficient
amount of them in the beginning.

BUG=609550

Review-Url: https://codereview.chromium.org/1976073002
Cr-Commit-Position: refs/heads/master@{#398049}
2 files changed