[Autofill Assistant] Move details into model.

Change-Id: I804c3314accef5590c02aba545f6f0ea84c654e1
Reviewed-on: https://chromium-review.googlesource.com/c/1430000
Commit-Queue: Jordan Demeulenaere <jdemeulenaere@chromium.org>
Auto-Submit: Jordan Demeulenaere <jdemeulenaere@chromium.org>
Reviewed-by: Stephane Zermatten <szermatt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625242}
12 files changed