Examine source code of Bring Back Twitter

{
  "name": "Bring Back Twitter",
  "icons": {
    "16": "assets/app-logo16.png",
    "32": "assets/app-logo32.png",
    "48": "assets/app-logo48.png",
    "128": "assets/app-logo128.png"
  },
  "version": "1.4",
  "permissions": [
    "storage"
  ],
  "description": "Brings back old Twitter UI",
  "host_permissions": [
    "https://*.twitter.com/*",
    "https://*.x.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://*.twitter.com/*",
        "https://*.x.com/*"
      ],
      "js": [
        "contentScript.js"
      ],
      "css": [
        "main.css"
      ]
    }
  ],
  "web_accessible_resources": [
    "assets/twitter-logo.png",
    "assets/twitter-logo128.png",
    "assets/twitter-logo48.png",
    "assets/twitter-logo32.png",
    "assets/twitter-logo16.png",
    "assets/verified-logo.png",
    "assets/verified-logo-white.png",
    "assets/verified-badge.svg",
    "assets/verified-badge-white.svg",
    "assets/verified-logo27.png"
  ],
  "action": {
    "default_icon": {
      "16": "assets/app-logo16.png",
      "32": "assets/app-logo32.png",
      "48": "assets/app-logo48.png",
      "128": "assets/app-logo128.png"
    },
    "default_title": "BringBackTwitter",
    "default_popup": "popup.html"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{16cf985b-01ce-4af9-b998-6a8992dc4191}"
    }
  }
}