Examine source code of Audio Selector

{
  "manifest_version": 3,
  "name": "Audio Selector",
  "version": "0.3.4",
  "description": "A powerful tool to route browser tab audio to any output device and manage your online meetings with ease.",
  "homepage_url": "https://github.com/OlexandrI/AudioSelector/",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "storage",
    "tabs",
    "activeTab",
    "scripting"
  ],
  "commands": {
    "select-audio-device": {
      "suggested_key": {
        "default": "Ctrl+Alt+A"
      },
      "description": "Change the audio output device for the current tab"
    },
    "meet-switch-tab": {
      "suggested_key": {
        "default": "Ctrl+Alt+G"
      },
      "description": "Switch to the next meet tab"
    },
    "meet-join": {
      "description": "Join the meeting switch to it (if have only one meet tab)"
    },
    "meet-toggle-microphone": {
      "suggested_key": {
        "default": "Alt+Shift+G"
      },
      "description": "Mute/Unmute the microphone for the active meet tab (without switching)"
    },
    "meet-toggle-camera": {
      "description": "Mute/Unmute the camera for the active meet tab (without switching)"
    }
  },
  "background": {
    "scripts": [
      "scripts/background.js"
    ]
  },
  "host_permissions": [
    "*://meet.google.com/*"
  ],
  "optional_host_permissions": [
    "*://*/*"
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "audioSelector@ctoinside.you"
    }
  }
}