Examine source code of Simple Calculator v3

{
  "manifest_version": 2,
  "name": "Simple Calculator",
  "version": "1.0",
  "description": "A simple calculator within your browser.",
  "browser_action": {
    "default_icon": "icons/calculator-48.png",
    "default_popup": "popup.html",
    "default_title": "Calculator"
  },
  "icons": {
    "48": "icons/calculator-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0eba49a1-102c-410d-bfac-f99b3ef2e9ff}"
    }
  }
}