Convert providers.js to use async-await.

Bug: 909056
Change-Id: I6ed186ccb13a6373c8ed0ef559a30892cc89dd1c
Reviewed-on: https://chromium-review.googlesource.com/c/1356169
Commit-Queue: Sam McNally <sammc@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612549}
1 file changed