Examine source code of Mute Switch

{
  "manifest_version": 2,
  "name": "Tab Mute Toggle",
  "version": "1.2",
  "description": "Mute/unmute the current tab with one click. Icons by Fathema Khanom - https://www.flaticon.com/free-icons/speaker",
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "32": "icons/unmute.png"
    },
    "default_title": "Mute/Unmute Tab"
  },
  "icons": {
    "32": "icons/unmute.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e13676fe-6163-4222-b375-a68cf537b48b}"
    }
  }
}