Examine source code of toolbar-calculator

{
  "manifest_version": 2,
  "name": "Calculator",
  "version": "1.0",
  "background": {
    "scripts": [
      "borderify.js"
    ]
  },
  "description": "Popup calculator for quick-basic calculations",
  "icons": {
    "48": "./icons/logocalc-48.png"
  },
  "browser_action": {
    "default_title": "Calculator",
    "default_popup": "./calculate.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c21b9d60-f49b-4e1d-8b45-ac9b8512b192}"
    }
  }
}