Examine source code of NitterRedirect

{
  "manifest_version": 2,
  "name": "NitterRedirect",
  "version": "1.0",
  "description": "Redirects twitter.com links to nitter.it",
  "homepage_url": "https://github.com/ArneVC/NitterRedirect",
  "icons": {
    "48": "icons/nitter_48.png",
    "96": "icons/nitter_96.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "storage"
  ],
  "background": {
    "scripts": [
      "NitterRedirect.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{486e0171-172a-426f-82a2-e51c5327583c}"
    }
  }
}