This bug has an owner, thus, it's been triaged. Changing status to "assigned".

APIs are resolved by other sub issues. We go with single thread and synchronized calling so operation scheduling is not urgent. Also we decide to make service stateless and short-lived.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/6da1727c693ef2ff813dd5a8ae99c66167204ecf

commit 6da1727c693ef2ff813dd5a8ae99c66167204ecf
Author: Xiaochu Liu <xiaochu@chromium.org>
Date: Thu Nov 15 16:11:40 2018

dlcservice: implement Uninstall API

This CL implements the Uninstall API.
* validate input DLC ID.
* checks that the DLC module is installed.
* calls update_engine to make sure no DLC operation is on-going.
* calls imageloader to unload a DLC module.
* deletes DLC module image.

BUG= chromium:852166 
TEST=unittest

Change-Id: Ic77bc94ba6a9f4eaf323aa6f0b71bbd1a437db70
Reviewed-on: https://chromium-review.googlesource.com/1321829
Commit-Ready: Xiaochu Liu <xiaochu@chromium.org>
Tested-by: Xiaochu Liu <xiaochu@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>

[modify] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/dlc_service_dbus_adaptor.cc
[modify] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/boot_slot_test.cc
[modify] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/boot_slot.h
[add] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/utils.cc
[modify] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/boot_slot.cc
[add] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/utils.h
[modify] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/BUILD.gn
[modify] https://crrev.com/6da1727c693ef2ff813dd5a8ae99c66167204ecf/dlcservice/dlc_service_dbus_adaptor_test.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/e915584432c915c00c89f16d685f23d3e3cc1ff7

commit e915584432c915c00c89f16d685f23d3e3cc1ff7
Author: Xiaochu Liu <xiaochu@chromium.org>
Date: Fri Nov 16 13:02:04 2018

dlcservice: implement Install API

This CL implements Install API:
* validate input DLC ID.
* checks that DLC module is in a clean state.
* calls update_engine to make sure no DLC operation is on-going.
* Create empty image files.
* calls update_engine to start DLC module installation.
* wait for update_engine to finish with a timeout.
* calls imageloader to mount the image.

This CL has made several assumptions in order to unblock
 crbug.com/852171 . See TODOs in the code for details.

BUG= chromium:852166 
TEST=unittest
CQ-DEPEND=CL:1321829

Change-Id: I2bdfaa9623a95b86d7833731ad6306b66cb3ccae
Reviewed-on: https://chromium-review.googlesource.com/1334494
Commit-Ready: Xiaochu Liu <xiaochu@chromium.org>
Tested-by: Xiaochu Liu <xiaochu@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>

[modify] https://crrev.com/e915584432c915c00c89f16d685f23d3e3cc1ff7/dlcservice/dlc_service_dbus_adaptor.cc
[modify] https://crrev.com/e915584432c915c00c89f16d685f23d3e3cc1ff7/dlcservice/dlc_service_dbus_adaptor.h
[modify] https://crrev.com/e915584432c915c00c89f16d685f23d3e3cc1ff7/dlcservice/dlc_service_dbus_adaptor_test.cc