Currently there's a TODO in   ServiceWorkerLoaderHelpers::CreateFetchRequest.

// TODO(kinuko): Implement request.request_body handling.
DCHECK(!request.request_body);

We should handle the case where request.request_body exists.

You can use ServiceWorkerURLRequestJob as a guide for this. I think we can just assume features::IsMojoBlobsEnabled() is on for this, and don't worry about handling the request body when that feature is disabled. I *think* that means we don't need to do the "FileSizeResolver" work that ServiceWorkerURLLoaderJob does (I assume ServiceWorkerFetchRequest::blob_uuid and blob_size are not relevant for MojoBlobs).

For now, also let's just get it working for ServiceWorkerURLLoaderJob, then work on ServiceWorkerSubresourceLoader later.