Also, the version of AddView that takes View* was renamed to
AddExistingView and is meant only for adding views that are already
owned by the host.

Chromium changes:

https://chromium.googlesource.com/chromium/src/+/6f83fdb6e7f3c941861a9d3f4214cbbfc06053c9

commit 6f83fdb6e7f3c941861a9d3f4214cbbfc06053c9
Author: Allen Bauer <kylixrd@chromium.org>
Date:   Wed Jun 12 15:17:04 2019 +0000

    Add unique_ptr versions of AddView() to GridLayout class.

    Bug: 945335

https://chromium.googlesource.com/chromium/src/+/5b736bf217aeaa765eff32bbb4d119b2932b854d

commit 5b736bf217aeaa765eff32bbb4d119b2932b854d
Author: Allen Bauer <kylixrd@chromium.org>
Date:   Thu Jun 27 17:58:30 2019 +0000

    Refactor more uses of GridLayout::AddView to use the std::unique_ptr<> version.

    Bug: 945335