Examine source code of Simple Calculator Popup

{
  "manifest_version": 2,
  "name": "Simple Calculator Popup",
  "version": "1.0",
  "description": "A minimal calculator in the popup window.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png",
    "default_title": "Simple Calculator"
  },
  "permissions": [],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b0efbbdb-8e18-422b-9b06-bbac65d6af5c}"
    }
  }
}