Examine source code of HuluFix

{
  "manifest_version": 3,
  "name": "HuluFix",
  "version": "1.0",
  "description": "Fixes hardware media controls on hulu.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "tabs"
  ],
  "host_permissions": [
    "*://*.hulu.com/*"
  ],
  "action": {
    "default_icon": {
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    },
    "default_title": "HuluFix",
    "default_popup": "popup/index.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.hulu.com/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "background": {
    "page": "background/background.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "hulufix@zandz",
      "strict_min_version": "109.0"
    }
  }
}