Examine source code of Simple Tab Sound Manager

{
  "manifest_version": 2,
  "name": "Simple Tab Sound Manager",
  "version": "1.0",
  "description": "A button to toggle sound on/off or adjust volume for each tab easily without visiting each webpage.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon-48.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e3138613-c0ee-48ff-87bb-fa72cdecb6ad}"
    }
  }
}