Xamarin Android open and close browser -- 2

Hello i have a code to open browser like bellow
i want to close that browser after say 10sec need a code snippet for that

async void OpenBrowser()
{
await Browser.OpenAsync("https://google.com", new BrowserLaunchOptions
{
LaunchMode = BrowserLaunchMode.SystemPreferred,
TitleMode = BrowserTitleMode.Hide

});
}