Examine source code of NoAdFocus

{
  "manifest_version": 2,
  "name": "NoAdFocus",
  "version": "1.0.1",
  "description": "Skip the 5 seconds like a time saving super hero.",
  "icons": {
    "1024": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://adfoc.us/serve*"
      ],
      "js": [
        "skip.js"
      ]
    }
  ]
}