Tests like WebAppPictureInPictureWindowControllerBrowserTest
now have a trivial standalone PWA to reference.

Requested in
https://chromium-review.googlesource.com/c/chromium/src/+/2062123/1/chrome/browser/picture_in_picture/picture_in_picture_window_controller_browsertest.cc#2534

Bug: 2062123
Change-Id: I65451ef09523c669c4e53634d9bcac2a3face288
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2066408
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Auto-Submit: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#743501}