Examine source code of CardTrader Cart Enhancer

{
  "manifest_version": 2,
  "name": "CardTrader Cart Prices",
  "version": "1.0",
  "description": "Shows 2-month low, average, trend and condition upgrade/downgrade prices for each card in your CardTrader cart. CardTrader Zero sellers only.",
  "author": "Mitaan",
  "homepage_url": "https://github.com/mitaan/cardtrader-cart-prices",
  "icons": {
    "48": "icons/icon48.png",
    "96": "icons/icon96.png"
  },
  "browser_action": {
    "default_icon": "icons/icon48.png",
    "default_popup": "popup.html",
    "default_title": "CardTrader Cart Prices"
  },
  "content_scripts": [
    {
      "matches": [
        "https://cardtrader.com/*/cart/edit*",
        "https://www.cardtrader.com/*/cart/edit*"
      ],
      "js": [
        "cart.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "permissions": [
    "storage",
    "https://cardtrader.com/*",
    "https://www.cardtrader.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "cardtrader-cart-prices@mitaan",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}