Remove ui::AcceleratorManagerDelegate

It was added in the early days of mustash to support the mus window
server. Now that we have WS2 / window service as a part of ash it isn't
needed anymore. It was only being used in tests.

Bug: 842365, 866526
Test: ui_base_unittests, ash_unittests, manually try accelerators
Change-Id: Ib156f42103ef21c6cdaf95183bf828d0959ad84e
Reviewed-on: https://chromium-review.googlesource.com/1225594
Reviewed-by: Scott Violet <[email protected]>
Commit-Queue: James Cook <[email protected]>
Cr-Commit-Position: refs/heads/master@{#591370}
8 files changed