Examine source code of Chess Timer Alert

{
  "manifest_version": 3,
  "name": "Chess Timer Alert",
  "version": "1.0",
  "description": "Plays a series of sounds when your clock is running out of time on chess.com or lichess.org.",
  "permissions": [
    "activeTab",
    "scripting",
    "storage"
  ],
  "action": {
    "default_popup": "popup/popup.html",
    "default_icon": "icons/icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.chess.com/*",
        "*://lichess.org/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "sounds/alert.wav"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "icons": {
    "48": "icons/icon48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@chess_timer_alert",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}