TrustStoreMac: cache calculated certificate trust settings.

SystemTrustStoreMac owns a global shared TrustStoreMac instance.

SystemTrustStoreMac::IsKnownRoot is now implemented using the
TrustStoreMac cache rather than known_roots_mac.cc (which is now only
used by the old verifier.)

Bug: 973648
Change-Id: I5acf59e6f82865a4acc0ea2993828eab5e4edbbe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1666274
Commit-Queue: Matt Mueller <mattm@chromium.org>
Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#673750}
6 files changed