Examine source code of BLOCKERu

{
  "manifest_version": 2,
  "name": "BLOCKERu",
  "version": "1.1",
  "description": "Видаляє русню з рекомендацій в ютубі!",
  "permissions": [
    "https://www.youtube.com/*"
  ],
  "icons": {
    "16": "16.png",
    "48": "48.png",
    "128": "128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": [
        "app.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{fb83550c-8729-444c-9e95-d2b55e91711e}"
    }
  }
}