Remove requestAppBanner from the DevTools protocol.

This CL removes the ability to request an app banner from DevTools. This
follows the removal of the explicit link to trigger this action in
https://crrev.com/c/1370371.

Follow-up CLs will implement a new AppBannerManager::DryRun method which
will be accessed by devtools in order to collect all errors from the
installability check to surface to developers.

BUG=915945

Change-Id: I2d95030965474ebb35d6f8882c1ff00eeeb6a29a
Reviewed-on: https://chromium-review.googlesource.com/c/1393126
Commit-Queue: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621025}
17 files changed