Examine source code of Note Calculator

{
  "manifest_version": 2,
  "name": "Note Calculator",
  "version": "1.0",
  "description": "Calculate total amount from different currency notes.",
  "icons": {
    "48": "icons/icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "48": "icons/icon.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{83d9e928-9cf7-4e56-affa-86212260a60d}"
    }
  }
}