Examine source code of FF Reader

{
  "manifest_version": 2,
  "name": "FF Reader",
  "version": "0.6.0",
  "description": "A simple extension for Firefox that activates Reader Mode",
  "homepage_url": "https://github.com/jfcandidofilho/ffreader",
  "icons": {
    "32": "icons/32.png",
    "48": "icons/48.png",
    "96": "icons/96.png",
    "128": "icons/128.png",
    "256": "icons/256.png",
    "512": "icons/512.png"
  },
  "developer": {
    "name": "J. F. Candido Filho"
  },
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/96.png",
    "default_title": "Read Mode"
  },
  "background": {
    "scripts": [
      "ffreader.js"
    ]
  }
}