Examine source code of Sphere Calculator

{
  "manifest_version": 2,
  "name": "Sphere Calculator",
  "version": "1.0",
  "description": "Calculates the surface area and volume of a sphere.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Sphere Calculator",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b0e81ad4-c29d-4673-9863-57fc54d043e6}"
    }
  }
}