Examine source code of Security Header Checker

{
  "manifest_version": 2,
  "name": "Security Header Checker",
  "version": "1.0.0",
  "description": "Check if a domain has HSTS enabled: max-age, includeSubDomains, and preload status.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{698fe427-e222-4ce6-80cb-e7016b419c30}",
      "strict_min_version": "96.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_icon": {
      "16": "static/icon16.png",
      "32": "static/icon32.png",
      "48": "static/icon48.png",
      "96": "static/icon96.png",
      "128": "static/icon128.png"
    },
    "default_title": "Security Header Checker",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "static/icon16.png",
    "32": "static/icon32.png",
    "48": "static/icon48.png",
    "96": "static/icon96.png",
    "128": "static/icon128.png"
  }
}