Examine source code of Scheduled Message Sender

{
  "manifest_version": 3,
  "name": "Scheduled Message Sender",
  "version": "1.0",
  "description": "Schedule and send messages automatically at a specified time.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "storage",
    "activeTab",
    "scripting"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "scheduled-message-sender@example.com"
    }
  }
}