Examine source code of Scientific Calculator

{
  "manifest_version": 2,
  "name": "Scientfic Calculator",
  "version": "1.0",
  "description": "A scientific calculator supporting the most common operations.",
  "homepage_url": "https://github.com/mischlox/calculator-firefox",
  "browser_action": {
    "default_icon": {
      "48": "icons/icon.png"
    },
    "default_title": "Scientific Calculator",
    "default_popup": "calculator.html"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b4253763-bd24-49f9-a6ee-0eb7876c79a0}"
    }
  }
}