GitLab

Allow a SourceId to be obtained and the url set to
app://[chrome|play]/id.

Add a new SourceType to govern the creation of urls
with scheme "app".

Bug: 841671
Change-Id: I1ed98722cdeb78ffd9944548901089e28f64181a
Reviewed-on: https://chromium-review.googlesource.com/1058736Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Paul Dyson <pdyson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569962}