Under classic/single-process mash: * The dbus::Bus instance is created in chrome and passed to ash in ShellInitParams. * Access to D-Bus clients is restricted to clients that will eventually be owned by the ash process. Under multi-process ash (mash): * AshDBusHelper creates its own dbus thread and dbus::Bus instance. * The D-Bus clients created in AshService are owned by the ash process. * The D-Bus services in AshDBusServices are owned by the ash process. See `//ash/README.md` for details on mash. See [Chrome OS D-Bus Usage in Chrome] for information about adding D-Bus services. [Chrome OS D-Bus Usage in Chrome]: https://chromium.googlesource.com/chromiumos/docs/+/HEAD/dbus_in_chrome.md