desktop-pwas: Test file handling with WebAppBrowserController

The file handling tests are now run with both WebAppBrowserController
and HostedAppBrowserController.

Bug: 966290
Change-Id: I3ec4abf6883dfb132a294c3707439607e3cb6233
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1727849
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Jay Harris <harrisjay@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682595}
7 files changed