Use OnceCallback on Mojo interfaces in services/ui/public

This CL flips `use_once_callback` flag on the Mojo code generator for
//services/ui/public, and fixes all compile errors after that. After
this CL, Mojo interfaces there service starts using base::OnceCallback
instead of base::Callback on its return value handling.

Bug: 714018
Change-Id: I9a0923249f3bb2b37319a118f742f384c90cf31f
Reviewed-on: https://chromium-review.googlesource.com/1151185
Reviewed-by: kylechar <kylechar@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578759}
7 files changed