Examine source code of Simple Calculator v4

{
  "manifest_version": 2,
  "name": "Simple Calculator",
  "version": "1.0",
  "description": "Perform basic arithmetic operations quickly and easily.",
  "icons": {
    "48": "icons/calculator-icon-48.png"
  },
  "permissions": [],
  "browser_action": {
    "default_icon": "icons/calculator-icon-48.png",
    "default_popup": "popup.html",
    "default_title": "Simple Calculator"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{12026e74-fad4-47f2-b68a-5fb230854a8f}"
    }
  }
}