Examine source code of YT Clean

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "YT Clean",
  "version": "0.6resigned1",
  "manifest_version": 2,
  "description": "Cleans up YT",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_title": "YT Clean"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*",
        "*://youtube.com/*"
      ],
      "js": [
        "index.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{490a3d85-c66f-40e4-87d4-260db3a08028}"
    }
  }
}