Examine source code of Behind the Curtain

{
  "description": "A Firefox extension supposed to help you find the backend of a website proxied by Cloudflare.",
  "manifest_version": 2,
  "name": "Behind the Curtain",
  "version": "1.3.2",
  "homepage_url": "https://github.com/DAMcraft/BehindTheCurtain",
  "icons": {
    "48": "icons/unproxied.png"
  },
  "permissions": [
    "activeTab",
    "*://*/*",
    "<all_urls>",
    "dns",
    "storage",
    "webRequest",
    "webRequestBlocking",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/unproxied.png",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{38bce309-7c10-43ea-a662-ee2345510f0c}"
    }
  }
}