The AttachRequestBodyBlobDataHandles method returns a boolean, and is called here:

https://cs.chromium.org/chromium/src/content/browser/loader/navigation_url_loader_network_service.cc?q=AttachRequestBodyBlobDataHandles&l=95

This needs to fail the request when it returns false.

I don't see how to fail this, so assigning to kinuko. LEt me know how I can fail the request and I'll make a patch.