device/fido: add support for getting PIN tokens.

Change-Id: Ie5738f1fdf317a82d6cfb31a33235b8b12934afe
Reviewed-on: https://chromium-review.googlesource.com/c/1475009
Commit-Queue: Adam Langley <agl@chromium.org>
Auto-Submit: Adam Langley <agl@chromium.org>
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#632866}
6 files changed