Examine source code of Chrono Popup

{
  "manifest_version": 2,
  "name": "Chrono Popup",
  "version": "1.0",
  "description": "Track elapsed time easily in a lightweight popup.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "64": "icon64.png",
      "128": "icon128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{907ed6bd-dc2b-47d1-9ff2-5d639221847b}",
      "strict_min_version": "109.0"
    }
  },
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  }
}