fixup! [ozone/wayland] Add clipboard support

This CL is a fixup of [1] and also reverts [2], making
all ozone_unittests run on linux.chromeos bots, without any skips,
for both xdg_v5 and xdg_v6 shell implementations.

Basically, CL brings some important code out of DCHECK. It was
not affecting me locally, because I either build with is_debug
or dcheck_always_on.

[1] https://crrev.com/c/976461
[2] https://crrev.com/c/1027030

R=rjkroege@chromium.org
TEST=ozone_unittests

BUG=578890

Change-Id: I18092d09df85e7aa78b85d208ba372504cd8ede9
Reviewed-on: https://chromium-review.googlesource.com/1028030
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#553650}
2 files changed