Examine source code of RPN Calculator

{
  "description": "Adds an RPN calculator as a browser action button.",
  "manifest_version": 2,
  "name": "RPN Calculator",
  "version": "1.2resigned1",
  "homepage_url": "https://github.com/mconca/rpn-web-ext",
  "icons": {
    "32": "icons/calc-32.png",
    "48": "icons/calc-48.png"
  },
  "browser_action": {
    "default_icon": {
      "32": "icons/calc-32.png",
      "48": "icons/calc-48.png"
    },
    "default_title": "RPN Calculator",
    "default_popup": "popup/rpncalc.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{13e55a13-d3a7-4703-acf0-ccfad11f30b8}"
    }
  }
}