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As the delegate is ultimately responsible for configuring fullscreen
the code adds a OnSystemUiVisibilityChangeListener. If the right
mode is entered in a short amount of time, the toast is shown.

I'm adding Skip-Translation-Screenshots-Check as I'm moving the
string, which has already been translated and didn't have a screenshot.

BUG=1127486
TEST=weblayer private tests verify this

Skip-Translation-Screenshots-Check: True
Change-Id: I788f9df3493b828e66afd57669f34d470865f60d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419661Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809107}