Examine source code of PassCheck for Steam

{
  "manifest_version": 3,
  "name": "PassCheck for Steam",
  "short_name": "PassCheck",
  "version": "1.1.3",
  "description": "Shows whether Steam games and wishlist items are available in the current PC Game Pass catalog.",
  "icons": {
    "32": "icons/passcheck-32.png",
    "48": "icons/passcheck-48.png",
    "96": "icons/passcheck-96.png",
    "128": "icons/passcheck-128.png"
  },
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "https://catalog.gamepass.com/*",
    "https://displaycatalog.mp.microsoft.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://store.steampowered.com/app/*",
        "https://store.steampowered.com/wishlist*",
        "https://store.steampowered.com/wishlist/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "passcheck-for-steam@toomy.local",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "strict_min_version": "140.0"
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}