Examine source code of signTextLSF

{
  "manifest_version": 2,
  "name": "signTextLSF",
  "description": "This extension emulates Netscape's crypto.signText() using LSF.",
  "version": "1.2",
  "author": "Information Services Plc.",
  "icons": {
    "16": "dist/icons/signTextLSF-16.png",
    "40": "dist/icons/signTextLSF-40.png",
    "48": "dist/icons/signTextLSF-48.png",
    "64": "dist/icons/signTextLSF-64.png",
    "128": "dist/icons/signTextLSF-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "dist/js/browser-polyfill.js",
        "dist/js/contentscript.js"
      ]
    }
  ],
  "permissions": [
    "http://127.0.0.1:8090/*",
    "http://127.0.0.1:23125/*",
    "http://127.0.0.1:53953/*",
    "https://127.0.0.1:8089/*",
    "https://127.0.0.1:23124/*",
    "https://127.0.0.1:53952/*"
  ],
  "web_accessible_resources": [
    "dist/js/script.js",
    "dist/css/signtext-modal.css"
  ],
  "browser_action": {
    "default_icon": "dist/icons/signTextLSF-48.png",
    "default_title": "Sign Text LSF",
    "default_popup": "dist/popup/popup.html"
  },
  "background": {
    "persistent": true,
    "scripts": [
      "dist/js/browser-polyfill.js",
      "dist/js/background.js"
    ]
  }
}