GitLab

Move GetArcAppIdByPackageName from AshMessageCenterClient to its own
C++ interface.

Also delete ash::mojom::AshMessageCenterClient since it's now empty.

Bug: 958191
Change-Id: I605ae6ae081e54010348dd3e9c4d01ece8aaaed4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1658846
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#670166}