Adding <keygen> Content Setting (Android UI)
This adds Android UI to allow the user to change the Content Setting to block/allow keygen usage on a per-site basis.
To trigger the exception, we also create a Content Exception on any site that uses a <keygen> element.
BUG=
514767
Committed:
https://crrev.com/34a7682cd49f8fdfb6a0f715a6118076f9ad8224
Cr-Commit-Position: refs/heads/master@{#370416}