GitLab

This moves some duplicate code to CoreFaviconService where it can
be shared.

BUG=1076463
TEST=none

Change-Id: I0f6a26221acf189e57cd12a16d2624bd598917b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2339388
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795202}