Rather than wrapping every sync D-Bus call with a GTask helper (hundreds of
additional lines of code and dozens of new entrypoints in libfwupd) I think it
is best for client software wanting async operation just uses the D-Bus
interface. I consider it part of the API as much as the shared library and
I don't see it changing in a non-compatible way any time soon.
Exposing these already-exported symbols allows client software to use the
demarshalling functionality and to operate on the GObjects directly from an
existing GDBus async return value.
This feature is turned on with the new fwupdtool option `--enable-json-state`
The intended use case is for ChromeOS to be able to save information about
devices on the system when `fwupdtool update` was run to display in the UX at
a later time.
