Clock

manifest.json

{
  "update_url": "http://clients2.google.com/service/update2/crx",
  "name": "Clock",
  "description": "description",
  "version": "1.0",
  "manifest_version": 2,
  "icons": {
    "16": "clock-16.png",
    "128": "clock-128.png"
  },
  "app": {
    "background": {
      "scripts": [
        "background.js"
      ]
    }
  }
}