GitLab

make ReadCallback and WriteCallback use base::OnceCallback

Bug: 1152282
Change-Id: Ie7c52a762e04c368fbecd0ed1dcec3c0ae8ab1c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2600384Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/master@{#839056}