GitLab

Add UKM metric that records SetBadge call per web app
to track the Badging API usage on SetAppBadge.
Review doc is at https://docs.google.com/document/d/1XNamCi2kjjGLQQ3uJtpYcZpxDTY1NlDnMBFBFjlybGk/edit

Bug: 1051682
Change-Id: Ia6a1829cd275f873bc5a72d087b873f3f301959e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108537Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Chris Mumford <cmumford@google.com>
Commit-Queue: Phillis Tang <phillis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760215}