[AF] Add integration tests for wallet metadata

This CL creates the first integration tests for the autofill wallet
metadata model type.

Bug: 894001
Change-Id: Ie756264fe6b22d863a6965456ec0d7b627774c23
Reviewed-on: https://chromium-review.googlesource.com/c/1306357
Commit-Queue: Jan Krcal <jkrcal@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607282}
7 files changed