Examine source code of Kinguin Deal Hunter

{
  "version": "1.0",
  "name": "Kinguin Deal Hunter",
  "description": "See the best offers while browsing Steam, EA, Epic Store, GOG and YouTube with product displays from Kinguin marketplace.",
  "author": "Michał Figas",
  "browser_action": {
    "default_popup": "menu.html",
    "default_icon": {
      "128": "assets/Kinguin_favicon.png"
    }
  },
  "icons": {
    "128": "assets/Kinguin_favicon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://store.steampowered.com/app/*",
        "https://store.epicgames.com/*",
        "https://www.origin.com/*",
        "https://www.ea.com/*",
        "https://www.gog.com/*",
        "https://www.youtube.com/*",
        "https://www.kinguin.net/*"
      ],
      "js": [
        "contentScript.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "tabs",
    "webNavigation",
    "storage",
    "notifications",
    "contextMenus",
    "https://kinguin.net/*",
    "https://www.kinguin.net/*",
    "https://static.kinguin.net/*",
    "https://api.steampowered.com/*",
    "https://steamcommunity.com/*",
    "https://store.steampowered.com/wishlist*"
  ],
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{d00ed493-776d-49b0-8a6e-6722634da172}"
    }
  }
}