GitLab

Split out from subsequent CL crrev.com/c/1897398 plus surrounding
cleanup.
Mostly refactoring except:
-remove deprecated metric logging.
-diverge when the "Open in PWA Window" menu item is enabled.
  Previously this used the same CanCreateWebApp check as "Create
  Shortcut" and "Install <PWA>".
  The presence of this item is already controlled separately (by
  checking whether the page is in scope of a PWA) so most of the checks
  in CanCreateWebApp are redundant. The relevant checks are within
  AreWebAppsUserInstallable (but just calling that method is answering
  a different question). So copied body of AreWebAppsUserInstallable.
  Subsequent CL will modify CanCreateWebApp.

Change-Id: Ib2a32b74637be89b6ac230f4d046e31316512680
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1989739
Commit-Queue: Glen Robertson <glenrob@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729655}