Examine source code of Error 404 Wayback Machine

{
  "manifest_version": 2,
  "name": "Error 404 Wayback Machine",
  "description": "Reduce annoying 404 pages by automatically checking for an archived copy in the Wayback Machine.",
  "version": "1.3resigned1",
  "homepage_url": "https://archive.org/",
  "icons": {
    "48": "images/icon.png",
    "96": "images/icon@2x.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "http://*/*",
    "https://*/*",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "scripts/background.js"
    ]
  },
  "web_accessible_resources": [
    "images/close.svg",
    "images/car.gif"
  ],
  "applications": {
    "gecko": {
      "id": "error404waybackmachine@lafleur.com",
      "strict_min_version": "42.0"
    }
  }
}