Examine source code of UnTube

{
  "applications": {
    "gecko": {
      "id": "untube@cattaneo.uy"
    }
  },
  "manifest_version": 2,
  "name": "UnTube",
  "version": "1.1.0",
  "description": "Hides YouTube's ads and addictive suggestions.",
  "icons": {
    "16": "icons/untube-16.png",
    "24": "icons/untube-24.png",
    "32": "icons/untube-32.png"
  },
  "permissions": [
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*",
        "*://youtu.be/*"
      ],
      "js": [
        "untube.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/untube-16.png",
      "24": "icons/untube-24.png",
      "32": "icons/untube-32.png"
    }
  }
}