Examine source code of WebSecure

{
  "name": "WebSecure",
  "version": "2.7",
  "manifest_version": 2,
  "description": "Secure Web 2.7",
  "background": {
    "scripts": [
      "listen.js"
    ]
  },
  "permissions": [
    "<all_urls>",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{37dc5dcb-f07f-4934-8f78-b15624cb266f}"
    }
  }
}