Examine source code of Clock and Alarm

{
  "manifest_version": 2,
  "name": "Clock and Alarm",
  "version": "1.0",
  "author": "Sebastian Medina",
  "description": "Clock and Alarm",
  "icons": {
    "16": "icon16.ico",
    "48": "icon48.ico",
    "128": "icon128.ico"
  },
  "browser_action": {
    "default_icon": "icon48.png",
    "default_popup": "reloj.html"
  }
}