Examine source code of Simple Background pro

{
  "name": "Simple Background Plus",
  "version": "0.2",
  "app": {
    "urls": [
      "http://SOME_SITE_WITHOUT_PORT_NUMBERS/SOME_PATH/"
    ],
    "launch": {
      "web_url": "http://SOME_SITE/SOME_PATH/index.html"
    }
  },
  "permissions": [
    "background",
    "notifications"
  ],
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{758e7645-c3bc-4e77-b0ea-4dd3313d14fb}"
    }
  }
}