Examine source code of Studio buttons

{
  "manifest_version": 2,
  "name": "Studio buttons",
  "version": "1.1",
  "description": "You get some more buttons in scratch studios.",
  "icons": {
    "64": "icons/logo-64.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://scratch.mit.edu/studios/*"
      ],
      "js": [
        "deleter.js"
      ]
    }
  ]
}