[iOS] Fix scroll end adjustment for hiding toolbar.

This CL updates BVC's fullscreen scroll end adjustment animation to
only update the top content padding early for header-hiding animations
that reveal beyond the top of the rendered content.  All other
scroll end adjustments can update the top content padding in the
animation's completion block.

Bug: 800697
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I3c53e39e6aec1f3ddad2c83aed9c109221780c49
Reviewed-on: https://chromium-review.googlesource.com/922269
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#538542}(cherry picked from commit 458bc43f9505182db53ad3e7368fc73b35ba3fde)
Reviewed-on: https://chromium-review.googlesource.com/935221
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Commit-Position: refs/branch-heads/3325@{#574}
Cr-Branched-From: bc084a8b5afa3744a74927344e304c02ae54189f-refs/heads/master@{#530369}
1 file changed