Remove TiclSettingsProvider

It only had one method, UseGCMChannel(), plus corresponding observer
infrastructure. All UseGCMChannel() implementations always returned
true, so the whole thing can be removed.

Note: All the "PushClient" stuff from jingle/notifier should also be
removed eventually, but right now lots of tests still depend on it.

Bug: 912042
Change-Id: I41a9d2a2401024b36e358bc7dc22a43159554584
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1530964
Reviewed-by: Tatiana Gornak <melandory@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#643375}
17 files changed