device/fido/mac: invalidate LAContext before deleting it

This causes any pending Touch ID consent prompt to be dismissed when the
authenticator is deleted, e.g. because the transaction was cancelled.
Otherwise the dialog sticks around until the OS lets it time out.

(See https://developer.apple.com/documentation/localauthentication/lacontext/1514192-invalidate?changes=_2.)

Bug: 678128
Change-Id: Ic4102b54ec78781ed869fa6a7827885ace5345e1
Reviewed-on: https://chromium-review.googlesource.com/1137218
Reviewed-by: Jun Choi <hongjunchoi@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#575729}
1 file changed