Examine source code of VA Autofill

{
  "manifest_version": 2,
  "name": "Field Assistant",
  "description": "Helps fill in form fields automatically.",
  "version": "0.9.3",
  "permissions": [
    "storage",
    "unlimitedStorage",
    "contextualIdentities",
    "cookies",
    "webNavigation",
    "*://tickets.museivaticani.va/*",
    "*://epay.catholica.va/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "vatican-ticket-autofill@va-ticket-tracker",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Field Assistant",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://tickets.museivaticani.va/*"
      ],
      "run_at": "document_end",
      "js": [
        "content-scripts/booking.js"
      ]
    },
    {
      "matches": [
        "*://epay.catholica.va/*"
      ],
      "run_at": "document_end",
      "js": [
        "content-scripts/epay.js"
      ]
    }
  ]
}