Examine source code of Spoilern't

{
  "manifest_version": 2,
  "name": "Spoilern't",
  "version": "1.2",
  "description": "Hides descriptions on Netflix",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.netflix.com/*"
      ],
      "js": [
        "spoilernt.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage"
  ],
  "applications": {
    "gecko": {
      "id": "{2fa882ef-7c61-4fe2-aeb5-bb56d51ceb4d}"
    }
  }
}