Examine source code of img-enlarger

{
  "manifest_version": 2,
  "name": "img-enlarger",
  "version": "1.0",
  "description": "Image enlarger for my-class",
  "icons": {
    "48": "icons/border-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "img-enlarger.css"
      ]
    }
  ]
}