[Files app] ES6 class for metadata_provider.js

Bug: 778674
Change-Id: Ibceb067e7358b8da9225899f25e2015e8b9ce789
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648296
Auto-Submit: François Degros <fdegros@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: François Degros <fdegros@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666957}
1 file changed