Examine source code of AgeCalculator

{
  "manifest_version": 3,
  "name": "Age Calculator",
  "version": "1.0",
  "description": "Calculate age from Date of Birth",
  "permissions": [],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon_16.png",
      "48": "icon_48.png",
      "128": "icon_128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "age-calculator@reddyaman.in",
      "strict_min_version": "109.0"
    }
  }
}