Examine source code of Link Checker fork

{
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "name": "Link Checker",
  "description": "Redirect Link Checker will check all links on your page to find broken and redirect links",
  "version": "1.2",
  "browser_action": {},
  "icons": {
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@checklinks-ng",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "websiteContent"
        ]
      }
    }
  },
  "permissions": [
    "storage",
    "tabs",
    "activeTab",
    "http://*/*",
    "https://*/*"
  ],
  "web_accessible_resources": [
    "redirectCheck.js"
  ]
}