Approach:
* The service worker manager will send a message to constellation with, its sender and a pipeline id, and a scope_url.

* The constellation on receiving the message will find the pipeline and send a message to its containing script thread
passing the SW manager sender.

* The `script_thread` on receiving the message will query its TLS `ServiceWorkerRegistration` (by `scope_url`) and retrieve the `Trusted<ServiceWorker>` by calling `get_trusted_worker()` on `ServiceWorkerRegistration` object , and send the `Trusted<ServiceWorker>` to the SW manager using the sender which it gets from the constellation.

So is this approach going in right direction ?