Examine source code of Calcrypto

{
  "manifest_version": 2,
  "name": "Calcrypto",
  "version": "1.0.4",
  "description": "A firefox extension to calculate prices within cryptocurrency and fiat currency.",
  "icons": {
    "48": "icons/icon.jpg"
  },
  "browser_action": {
    "default_icon": "icons/icon.jpg",
    "default_title": "Calcrypto",
    "default_popup": "popup/main_popup.html"
  },
  "permissions": [
    "https://api.coinmarketcap.com/",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{328ee400-9bdc-4de6-9370-d1e58a8ac97d}"
    }
  }
}