GitLab

To FaviconDatabase. I'm going to use this in weblayer code
to expire favicons. WebLayer doesn't use history, but needs
a way to prune the database.

BUG=1076463
TEST=covered by tests

Change-Id: If74a389a947eb465447009c620e0988f9545ab91
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354998
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798209}