[Autofill Assistant] Removed overlay from the layout. This is now part of the TouchEventFilter.

Essentially, this is accomplished by setting a TouchEventFilter with no touch-able area. This will gray out the entire view and look exactly like the overlay used to look.

Also, the unexpected tap counter is now reset each time a TouchEventFilter is disabled. This should result in more consistent and predictive behavior.

Bug: 806868
Change-Id: I308a3dc488e8d778245bfdc88714d1a9e621c8df
Reviewed-on: https://chromium-review.googlesource.com/c/1335940
Commit-Queue: Clemens Arbesser <arbesser@google.com>
Reviewed-by: Theresa <twellington@chromium.org>
Reviewed-by: Stephane Zermatten <szermatt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608387}