Examine source code of Notifier for Google Voice

{
  "manifest_version": 3,
  "name": "Notifier for Google Voice",
  "version": "1.0.7",
  "description": "Shows unread conversations from Google Voice inbox.",
  "options_page": "options.html",
  "permissions": [
    "alarms",
    "tabs",
    "scripting",
    "storage"
  ],
  "host_permissions": [
    "https://voice.google.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_icon": {
      "16": "icon_16.png",
      "32": "icon_32.png",
      "48": "icon_48.png",
      "128": "icon_128.png"
    },
    "default_title": "Notifier for Google Voice"
  },
  "icons": {
    "16": "icon_16.png",
    "32": "icon_32.png",
    "48": "icon_48.png",
    "128": "icon_128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "notifier-for-google-voice@marksowell.com",
      "strict_min_version": "109.0"
    }
  }
}