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" 
    ]
  }
}