🎫 Notify observers of InstalledWebappProvider on state change.

This change is apart of a larger sequence of CLs for implementing
notification delegation auto-enrolment. See https://crbug.com/945258.

Specifically this change hooks up the plumbing put in place in
https://chromium-review.googlesource.com/c/chromium/src/+/1554676 .

Bug: 949146
Change-Id: Ib4be244acb751c28ab9dc7c1f46d9694b83b071a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1572127
Commit-Queue: Peter Conn <peconn@chromium.org>
Reviewed-by: Michael van Ouwerkerk <mvanouwerkerk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652142}
3 files changed