Examine source code of Auto Mute Background Tabs

{
  "manifest_version": 2,
  "name": "Auto Mute Background Tabs",
  "version": "1.0",
  "description": "Automatically mutes background tabs in Firefox.",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a3786739-df1a-4c01-860b-a92bbf44fae6}"
    }
  }
}