Lookalike URLs: Exclude registry when doing edit distance comparison

The edit distance heuristic in Lookalike URLs feature records a match
if the navigated domain is one edit distance away from one of the top
500 domains. However, it takes the registry of the domains into account
as well, causing bogus matches.

As an example, it matches google.com.tw to google.com.tr (top domain),
even though the former is unlikely to be a spoofing attempt. This CL
correctly handles this case.

Bug: 913647
Change-Id: Ifa04a3f6eeccd0b97dde364d3cd2ef3d415f6ef1
Reviewed-on: https://chromium-review.googlesource.com/c/1396304
Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Cait Phillips <caitkp@chromium.org>
Commit-Queue: Mustafa Emre Acer <meacer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620877}
7 files changed