Adds a global preference observer that is notified whenever any
preference value is updated. This is used to support runtime
configuration of WebXR automated testing, which is a prerequisite for
running multiple WPT tests in a single browser session.
Testing: Ran `./mach test-wpt /webxr --product=servodriver`
Fixes: #38647
---------
Signed-off-by: Josh Matthews <josh@joshmatthews.net>
This will prevent rust-analyzer from suggesting the import of these
types when dealing with `crossbeam` channels.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
- Run `cargo fmt` on `webxr` and `webxr-api`
- Fix clippy warnings in the existing `webxr` code
- Integrate the new crates into the workspace
- Expose `webxr` via the libservo API rather than requiring embedders to
depend on it explicitly.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
