Examine source code of YouToo Adjust

{
  "manifest_version": 2,
  "name": "YouToo Adjust",
  "version": "1.1.2",
  "description": "Adjusts the size of the YouTube player to fill the screen. No more titles getting in the way of the full-screen experience!",
  "icons": {
    "48": "icons/YTA-48.png",
    "96": "icons/YTA-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "css": [
        "adjust.css"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{c41f269b-ffd2-4804-a3f4-da2ceafcba36}"
    }
  }
}