Security drop fullscreen for any nested WebContents level.

BUG=873080
TEST=as in bug

Change-Id: Icd75715ac42789c84870967b11c9917a972ae086
Reviewed-on: https://chromium-review.googlesource.com/1173342
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Sidney San Martín <sdy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582970}
3 files changed