Backport all pending patches from chromium68 to upstream Chromium Ozone Wayland backend to webosose/chromium68 tree.

Some additional details:

• We want to keep being able to choose in build time the wayland backend. For that there is the neva.gni ozone_platform_wayland_external variable that should be true using intel backend at ozone/ and defines OZONE_PLATFORM_WAYLAND_EXTERNAL in that case.
• This is strictly for making chromium68 work on desktop with both backends, using NEVA build. Not for Yocto.
• We can have a branch for preparing this work, that is independent of any agl branch. But we prefer to have a baseline that is compatible with our AGL work. So recommendation is branching from submissions/15 and name the branch as @15.upstream_ozone_wayland