Examine source code of Ultrawidey

{
  "manifest_version": 2,
  "name": "Ultrawidey",
  "version": "2.5resigned1",
  "description": "Ultrawidy will provide an 21:9 aspect ratio to a lot of video streaming services, mostly it requires no button press for it to fit the 21:9 ratio, but please note that videos with an black borders can be removed by pressing ‘Z’. and by pressing 'X' you can force the 21:9 aspect ratio, this might be handy on some sites.",
  "icons": {
    "48": "icons/ultraWide.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "main.js",
        "videomod.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f400f50e-a470-49be-94cc-e0141471478a}"
    }
  }
}