GitLab

https://chromium-review.googlesource.com/c/chromium/src/+/1886898 has
recently switched to reading favicons on demand from a dedicated server,
so the traffic caused by sync-ing history favicons can be spared.

This patch achieves so by enabling an existing feature toggle.

One additional aspect is addressed, overlooked previously in
https://chromium-review.googlesource.com/c/chromium/src/+/1653428: the
local copy of favicons as persisted by sync (pseudo-USS) must be cleaned
up to avoid indefinitely leaking such data locally.

Bug: 978775
Change-Id: I7bf0c8d05348b5399cd3c5bc9f8675cd013d600e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1917173
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: vitaliii <vitaliii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719602}