chromium/chrome/test/data/extensions/api_test/worker/manifest.json

{
  "version": "1.0",
  "manifest_version": 2,
  "name": "Workers in extensions",
  "permissions": [
    "http://*/*"
   ],
  "background": {
    "scripts": [ "background.js" ]
  },
  "content_security_policy": "script-src 'self' http://127.0.0.1:* http://localhost:*; object-src 'self'"
}