Examine source code of Link Checker

{
  "manifest_version": 2,
  "name": "Link Checker",
  "version": "10",
  "description": "Check all hyperlinks on a page for broken URLs. Filter by status, see HTTP codes live.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{24edfe81-9592-4bd9-b8fc-0b317ebe39a5}",
      "strict_min_version": "96.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_icon": {
      "16": "assets/icons/icon16.png",
      "32": "assets/icons/icon32.png",
      "48": "assets/icons/icon48.png",
      "96": "assets/icons/icon96.png",
      "128": "assets/icons/icon128.png"
    },
    "default_title": "Link Checker",
    "default_popup": "src/popup.html"
  },
  "icons": {
    "16": "assets/icons/icon16.png",
    "32": "assets/icons/icon32.png",
    "48": "assets/icons/icon48.png",
    "96": "assets/icons/icon96.png",
    "128": "assets/icons/icon128.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "src/content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}