Examine source code of Check Web links

{
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "name": "Check Web links",
  "description": "We will check all links on your page to find broken and redirect links.",
  "version": "1.2.2",
  "browser_action": {
    "default_icon": {
      "16": "icons/16.png",
      "32": "icons/32.png",
      "48": "icons/48.png",
      "64": "icons/64.png",
      "128": "icons/128.png"
    }
  },
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "64": "icons/64.png",
    "128": "icons/128.png",
    "256": "icons/256.png",
    "512": "icons/512.png"
  },
  "applications": {
    "gecko": {
      "id": "@checkWebLinks",
      "strict_min_version": "57.0"
    }
  },
  "permissions": [
    "storage",
    "tabs",
    "activeTab",
    "http://*/*",
    "https://*/*"
  ],
  "web_accessible_resources": [
    "redirectCheck.js"
  ]
}