[iOS]History sync can be dismissed with esc

This is consistent with the fact that it can be dismissed by sliding
or by tapping outside of the view.

Fixed: 402806995
Change-Id: I3c68abdbbd7ed12a6c721d011729b3eb1ae51772
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6348577
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Auto-Submit: Arthur Milchior <arthurmilchior@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1431946}