Examine source code of Jam Player

{
  "manifest_version": 3,
  "name": "Jam Player",
  "version": "0.2.0",
  "author": "ELginas",
  "homepage_url": "https://github.com/ELginas/jam-player",
  "description": "Playtest game jam games faster and easier.",
  "browser_specific_settings": {
    "gecko": {
      "id": "jam-player@elginas"
    }
  },
  "icons": {
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "background": {
    "type": "module",
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://itch.io/*"
      ],
      "js": [
        "hook.js"
      ],
      "run_at": "document_start",
      "world": "MAIN"
    },
    {
      "matches": [
        "https://itch.io/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "assets/AddToQueue.svg",
        "assets/RemoveFromQueue.svg"
      ],
      "matches": [
        "https://itch.io/*"
      ]
    }
  ],
  "permissions": [
    "storage",
    "tabs",
    "cookies",
    "contextualIdentities"
  ],
  "options_ui": {
    "page": "options.html"
  }
}