Examine source code of Print Button

{
  "version": "0.1.4",
  "manifest_version": 2,
  "name": "Print Button",
  "short_name": "print-button",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "homepage_url": "http://mybrowseraddon.com/print.html",
  "permissions": [
    "storage",
    "activeTab",
    "contextMenus"
  ],
  "description": "Easily print any page with just one click!",
  "browser_action": {
    "default_title": "Print Button",
    "default_icon": {
      "16": "data/icons/16.png",
      "32": "data/icons/32.png",
      "48": "data/icons/48.png",
      "64": "data/icons/64.png"
    }
  },
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png"
  }
}