Examine source code of Get Browser Version

{
  "name": "Browser Version",
  "description": "Get browser version with command.",
  "manifest_version": 2,
  "version": "0.3.0",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "clipboardWrite",
    "contextMenus",
    "notifications"
  ],
  "commands": {
    "get-browser-version": {
      "suggested_key": {
        "default": "Alt+Shift+V",
        "mac": "Alt+Shift+V"
      },
      "description": "Copy browser version to clipboard."
    }
  }
}