Examine source code of Better Calculator

{
  "manifest_version": 2,
  "name": "Better Calculator",
  "description": "Browser toolbar calculator, including arithmetic, exponents, trigonometry, and logarithms, respecting the order of operations.",
  "version": "1.4",
  "icons": {
    "48": "icon_48.png",
    "96": "icon_96.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Better Calculator"
  }
}