It uses the org.gnome.SettingsDaemon.Power.Screen D-Bus API. Currently
brightness set if the proxy is not ready are ignored; whether the
brightness value should be cached and set once it appears or whether
color profiles should be reapplied is yet to be decided.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2165>
Create a color manager type that eventually will be the high level
manager of color related behavior, such as ICC profiles and
color "temperature" a.k.a. night light.
For now, it's only an empty shell. It's also constructed by the actual
backend, as at a later point, the X11 and native color management
implementations will differ.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2141>