Examine source code of Tab OpenClose Sound

{
  "manifest_version": 2,
  "name": "Tab OpenClose Sound",
  "version": "1.0",
  "description": "Plays a sound when opening or closing tabs (pop/click).",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{31f13381-106d-4b0b-9dba-0db140339c36}"
    }
  }
}