User to confirm credentials if an accessibility service changes encryption.

When an accessibility service is enabled we are not using the user secure
lock when encrypting the data. If the latter is already used for encryption
we are decreasing the encryption level and therefore shall challenge the
user with their secure lock.

bug:17881324

Change-Id: If8905c05e20bc6bb6a6415e501871e5ad83f3d86
8 files changed