Examine source code of Proxy Selector

{
  "manifest_version" : 2 ,
  "name" : "Proxy Selector",
  "version" : "1.0",
  "description" : "Set up different proxy profiles by nickname.",
  "permissions" : [
    "proxy" ,
    "storage" 
  ],
  "applications": {
    "gecko": {
      "id": "proxyselector@example.com",
      "strict_min_version": "91.1.0"
    }
  },
  "background" : {
    "scripts" : [
      "background.js" 
    ]
  },
  "browser_action" : {
    "default_popup" : "popup.html",
    "default_title" : "Proxy Selector"
  }
}