GitLab

Also changes Installable to an enum class to avoid accidental
implicit casts to bools.

Bug: 801940
Change-Id: I186d878b338375e339b3b5eb24fa5f2abd6c975a
Reviewed-on: https://chromium-review.googlesource.com/981835Reviewed-by: Matt Giuca <mgiuca@chromium.org>
Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550502}