Examine source code of Checkey

{
  "name": "Checkey",
  "author": "Leonardo Capone (Esquiafo)",
  "version": "4.1.2",
  "description": "Check for the best price for yours keys",
  "icons": {
    "16": "logo/icon-16.png",
    "48": "logo/icon-48.png",
    "128": "logo/icon-128.png"
  },
  "minimum_chrome_version": "93",
  "background": {
    "scripts": [
      "js/worker-loader.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://store.steampowered.com/app/*"
      ],
      "js": [
        "js/content.js",
        "scripts/gamerpower.js",
        "scripts/nuuvem.js",
        "scripts/gamebillet.js",
        "scripts/instantgaming.js",
        "scripts/g2play.js",
        "scripts/kinguin.js",
        "scripts/gamivo.js",
        "scripts/hrkgame.js",
        "scripts/wingamestore.js",
        "scripts/joybuggy.js",
        "scripts/g2a.js",
        "scripts/steamdb.js",
        "scripts/dreamgame.js",
        "scripts/indiegala.js",
        "scripts/indiegala_m.js",
        "scripts/twogame.js",
        "scripts/humble.js",
        "scripts/xboxstore.js",
        "scripts/cdkeys.js",
        "scripts/fanatical.js",
        "scripts/gamersgate.js",
        "scripts/greengaming.js",
        "scripts/eneba.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "Checkey",
    "default_icon": {
      "16": "logo/icon-16.png",
      "32": "logo/icon-32.png",
      "48": "logo/icon-48.png",
      "128": "logo/icon-128.png"
    }
  },
  "permissions": [
    "cookies",
    "storage",
    "https://*.gamerpower.com/*",
    "https://*.nuuvem.com/*",
    "https://*.gamebillet.com/*",
    "https://*.gamivo.com/*",
    "https://*.g2play.net/*",
    "https://*.hrkgame.com/*",
    "https://*.instant-gaming.com/*",
    "https://*.k4g.com/*",
    "https://*.kinguin.net/*",
    "https://www.joybuggy.com/*",
    "https://*.wingamestore.com/*",
    "https://*.eneba.com/*",
    "https://catalog.gamepass.com/*",
    "https://*.displaycatalog.mp.microsoft.com/*",
    "https://*.g2a.com/*",
    "https://*.steamdb.com/*",
    "https://*.cdkeys.com/*",
    "https://*.humblebundle.com/*",
    "https://*.xbox.com/*",
    "https://*.microsoft.com/*",
    "https://*.dreamgame.com/*",
    "https://*.trustpilot.com/*",
    "https://*.indiegala.com/*",
    "https://*.2game.com/*",
    "https://*.fanatical.com/*",
    "https://*.store.epicgames.com/*",
    "https://*.gamesplanet.com/*",
    "https://*.gamersgate.com/*",
    "https://*.greenmangaming.com/*"
  ],
  "content_security_policy": "script-src 'self' https://www.nuuvem.com/* https://www.gamerpower.com/* https://www.joybuggy.com/* https://*.wingamestore.com/* https://*.wingamestore.com/*  https://*.eneba.com/* https://*.catalog.gamepass.com/* https://catalog.gamepass.com/* https://*.displaycatalog.mp.microsoft.com/* https://*.xbox.com/* https://*.gamebillet.com/* https://*.greenmangaming.com/* https://*.gamersgate.com/* https://*.gamesplanet.com/* https://*.steamdb.com https://*.g2a.com/* https://*.cdkeys.com https://*.humblebundle.com https://*.microsoft.com https://*.dreamgame.com https://*.trustpilot.com https://*.indiegala.com https://*.2game.com https://*.fanatical.com https://*.store.epicgames.com/*; object-src 'self'",
  "incognito": "spanning",
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{7512536a-0176-4cbe-8dc4-ccf53057d1fd}"
    }
  }
}