Examine source code of Readability Toggle

{
  "manifest_version" : 2 ,
  "name" : "Readability Toggle",
  "version" : "1.0.1",
  "description" : "Toggle a lightweight readability mode for the current page.",
  "browser_specific_settings": {
    "gecko": {
      "id": "readability-toggle@example.com",
      "strict_min_version": "78.0"
    }
  },
  "icons" : {
    "48" : "icon.svg"
  },
  "permissions" : [
    "activeTab" ,
    "storage" 
  ],
  "background" : {
    "scripts" : [
      "background.js" 
    ],
    "persistent" : false 
  },
  "browser_action" : {
    "default_popup" : "popup.html",
    "default_icon" : "icon.svg"
  }
}