GitLab

Provide TimestampToTimeDeltaDelay as a static helper method of
MidiService, and use it to calculate a delay time for a timestamp
to post a delayed task.

Bug: 672793
Change-Id: I7307bb816c262073ceae557ad9345c451051d414
Reviewed-on: https://chromium-review.googlesource.com/656924
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501595}