Examine source code of Easy XSS

{
  "manifest_version": 2,
  "name": "Easy XSS",
  "description": "XSS made easy",
  "version": "1.1resigned1",
  "default_locale": "en",
  "applications": {
    "gecko": {
      "strict_min_version": "56.0a1",
      "id": "{07414fb5-d993-468f-ba39-dd1ac8438b4a}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "menus",
    "activeTab",
    "clipboardRead",
    "clipboardWrite"
  ]
}