Examine source code of Customizable Alert Sounds

{
  "description": "__MSG_extensionDescription__",
  "icons": {
    "512": "icons/icon.png"
  },
  "version": "2.0",
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "permissions": [
    "alarms",
    "notifications"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "91.1.0",
      "id": "{ea1bea5b-a010-4494-9e35-adf3514f61f4}"
    }
  }
}