GitLab

This CL:
(1) Displays a confirmation dialog when users request that the host
    device be removed.
(2) Actually removes the device as a host if the user confirms their
    intention to forget the current device.

Note: As part of this change, I've moved some strings from
chromeos_strings.grdp to settings_strings.grdp, since the strings are
displayed in the settings page.

Bug: 870069, 824568
Change-Id: Ifd9fb275fa385d4fcc45cd4d8000c4534cd3c14b
Reviewed-on: https://chromium-review.googlesource.com/1191523Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586421}