Examine source code of Youter

{
  "manifest_version": 2,
  "name": "Youter",
  "description": "Fix 1 minute problem in youtube",
  "version": "1.0.4",
  "icons": {
    "48": "icons/icon_48.png",
    "96": "icons/icon_96.png"
  },
  "author": "Kia Hamedi",
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "app.js"
      ]
    }
  ],
  "browser_action": {
    "browser_style": true,
    "default_title": "Youter",
    "default_icon": "icons/icon_96.png",
    "default_popup": "popup/index.html"
  },
  "permissions": [
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{642640c5-56ef-42e4-ba3c-8ff5a08004fe}"
    }
  }
}