From https://phabricator.services.mozilla.com/D140732#inline-775467

for the extensions background service worker, we wouldn't have a remoteTab to pass to registerTraceableChannel and so we may need to think of a strategy to properly support filterResponseData when called from a service worker context

• one possible approach may be to still create an empty background page context to use internally for the StreamFilters created from a background service worker (this may be a reasonable approach if we will need also to implement other Extensions APIs that would need to fill gaps in the DOM API available directly in the worker context if we don't plan to rewrite those to also work in the service worker even besides the MV3 extensions use case
• another approach would be to look if we could use another approach to track when the traceable channel is meant to be destroyed because the related extension context has been destroyed (at least from what I recall that is the main purpose of passing that remoteTab when calling that registerTraceableChannel internal helper function)