Prevent app banners when a matching hosted/bookmark app exists on ChromeOS.
App banners currently do not check if there is an existing matching
bookmark or hosted app, e.g. added with the "Add to shelf" menu item.
This CL adds a check of all installed extensions for any pinned app
which matches the site requesting a banner on ChromeOS. On other desktop
platforms, the pinned check is currently not made, and app banners
are blocked if there is any matching bookmark app installed.
BUG=508000
R=benwells
Review URL: https://codereview.chromium.org/
1225863008
Cr-Commit-Position: refs/heads/master@{#338212}