Migrate //printing to OnceCallback

This updates //printing to use base::OnceCallback instead of legacy
base::Callback. No intended functional change is included.

This reduces the number of 'base::Bind' in //printing from 2 to 0 as
tracked at http://goo.gl/LUVhDj

Bug: 714018
Change-Id: Ic5ba394447c20b444d238511473bbfc7abbc9669
Reviewed-on: https://chromium-review.googlesource.com/954883
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542071}
2 files changed