Examine source code of Chess Time Warnings

{
  "manifest_version": 2,
  "name": "Chess Time Warnings",
  "version": "1.0.4",
  "description": "Audio warnings for chess time remaining on chess.com and lichess.org",
  "permissions": [
    "storage",
    "activeTab",
    "https://www.chess.com/*",
    "https://lichess.org/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/favicon16.png",
      "48": "icons/favicon48.png",
      "128": "icons/favicon128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.chess.com/*",
        "https://lichess.org/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "web_accessible_resources": [
    "sounds/*.wav"
  ],
  "icons": {
    "16": "icons/favicon16.png",
    "48": "icons/favicon48.png",
    "128": "icons/favicon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "chess-time-warnings@example.com",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}