Migrate MtpDeviceManager to OnceCallback.

This CL migrated to as many OnceCallback(s) as possible in
services/device/media_transfer_protocol directory. Due to some
unchanged DBus interfaces, there are still several base::Bind()
left in the implementation.

BUG=714018

Change-Id: Iceb2558f45a54e43503fc67fe40380cc9baef248
Reviewed-on: https://chromium-review.googlesource.com/1111693
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Donna Wu <donna.wu@intel.com>
Cr-Commit-Position: refs/heads/master@{#570676}
3 files changed