[AF][IOS] Takes secondary toolbar into account in CC save infobar (Part 2)

This CL moves the logic to set the infobar's bottom margin from
|-layoutSubviews| to |-sizeThatFits:|. The former method doesn't
always get called after the secondary toolbar disappears in
landscape mode. The latter does get called more reliably in both
portrait and landscape modes.
Also provides comments on why |-setFrame:| is overridden.

Bug: 849433
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I3ce410378d60535178a0c0c9d0f12f11948772ba
Reviewed-on: https://chromium-review.googlesource.com/1112303
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574291}
1 file changed