Add non-host functionality to the previews blacklist

This adds a rule to prevent previews navigations when j of k of the last
previews navigations in the past x days were opted out of regardless of
the host. j, k, and x are remotely controlled via finch but are
defaulted to 4, 10, and 100*365 by default.

BUG=639091

Review-Url: https://codereview.chromium.org/2442013003
Cr-Commit-Position: refs/heads/master@{#430371}
10 files changed