chromium/chrome/test/data/extensions/background_app/manifest.json

{
    "background": {
        "scripts": [ "background.js" ]
    },
   "description": "A simple app with background permission set.",
   "manifest_version": 2,
   "name": "Background App",
   "permissions": [ "background" ],
   "update_url": "http://clients2.google.com/service/update2/crx",
   "version": "1.2"
}