GitLab

Add a Mojo interface - AccountManagerObserver - for ash-chrome to send
account update notifications to lacros-chrome.

Bug: 1117478
Test: unit_tests --gtest_filter="*AccountManagerAshTest*"
Change-Id: I986676d3a635bdc3e50abd9d7489ea0645c2286d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2453259
Commit-Queue: Kush Sinha <sinhak@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815175}