Examine source code of CO2 Calculator

{
  "manifest_version": 2,
  "name": "CO2 Calculator",
  "version": "3.0",
  "description": "See how much CO₂ emissions and money you save by biking instead of driving!",
  "icons": {
    "48": "favicon/apple-touch-icon-48.png",
    "96": "favicon/apple-touch-icon-96.png",
    "128": "favicon/apple-touch-icon-128.png"
  },
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "CO2 Calculator",
    "default_icon": {
      "48": "favicon/apple-touch-icon-48.png",
      "96": "favicon/apple-touch-icon-96.png",
      "128": "favicon/apple-touch-icon-128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "co2-calculator@mbay.dev",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": []
}