Examine source code of Nope

{
  "manifest_version": 2,
  "name": "nope",
  "version": "1.1",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "description": "Blocks given domains for a given period of time, helping you to stay focused.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/icon-32.png",
    "default_title": "Nope",
    "default_popup": "popup/nope.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "nope.js"
      ],
      "run_at": "document_end"
    }
  ]
}