Mash cleanup: message center part 7.

Move SetArcNotificationsInstance from mojom to C++ interface. Remove
mojom::AshMessageCenterController.

Bug: 958191
Change-Id: Ic60e167d249549057d17a9e3d74e86bc2f45b9a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1663940
Reviewed-by: Xiyuan Xia <[email protected]>
Reviewed-by: Yusuke Sato <[email protected]>
Reviewed-by: Tom Sepez <[email protected]>
Commit-Queue: Evan Stade <[email protected]>
Cr-Commit-Position: refs/heads/master@{#671000}
13 files changed