The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a410274678c7e52ad5f40d93da684c63e3c9a019

commit a410274678c7e52ad5f40d93da684c63e3c9a019
Author: Risan <risan@chromium.org>
Date: Wed Feb 28 08:39:04 2018

ArcVolumeMounter: Send all mounts in UI Thread

As noticed by hashimoto@ and lhchavez@ in ag/938683, we actually need to perform this
in UI Thread instead of blocking pools. We are still posting the task to
a thread to keep the non-blocking I/O behaviour.

Bug:  chromium:816816 
Change-Id: I607f515e335bb48e074caa60a67835074d179558
Reviewed-on: https://chromium-review.googlesource.com/939065
Commit-Queue: Risan <risan@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Reviewed-by: Luis Hector Chavez <lhchavez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539759}
[modify] https://crrev.com/a410274678c7e52ad5f40d93da684c63e3c9a019/components/arc/volume_mounter/arc_volume_mounter_bridge.cc
[modify] https://crrev.com/a410274678c7e52ad5f40d93da684c63e3c9a019/components/arc/volume_mounter/arc_volume_mounter_bridge.h