Examine source code of Flipping Heck

{
  "manifest_version": 2,
  "name": "Flipping Heck",
  "version": "1.0",
  "description": "This is a prank extension. Every second, it flips an element in the page upside dowm.",
  "icons": {
    "48": "icon.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "index.js"
      ]
    }
  ]
}