Autoplay/PWA: set web_app_scope preference on desktop.

This will make desktop PWA have autoplay privileges in their scope.

Bug: 923910, 794874
Change-Id: Ie9895140c7892d8cace1f09054f527aba6858f09
Reviewed-on: https://chromium-review.googlesource.com/c/1436574
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Auto-Submit: Mounir Lamouri <mlamouri@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#628013}(cherry picked from commit 6926107f34d236e430df08ea5dc9a5327c17ed41)
Reviewed-on: https://chromium-review.googlesource.com/c/1450455
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/branch-heads/3683@{#132}
Cr-Branched-From: e51029943e0a38dd794b73caaf6373d5496ae783-refs/heads/master@{#625896}
5 files changed