Xamarin Cross menu burger iOS and Android!

I created a xamarin forms portable project after I created a class with the drop down menu, I would like to know how to align the image of the xamarin in the center, since I am not able to

using Xamarin.Forms;

namespace MenuHamburguerNavegacao
{
   public class NavigationDrawer : MasterDetailPage
    {
        public NavigationDrawer()
        {
            Title = "Navigation drawer";
            //descrição que irá aparecer no menu a esquerda
            string[] myPageNames = { "Home", "Second", "Third" };

            ListView listView = new ListView
            {
                ItemsSource = myPageNames,
            };

            this.Master = new ContentPage
            {

                Title = "Options",
                Content = listView,
                Icon = "beMobileMenuIconGray.png"
            };

            listView.ItemTapped += (sender, e) =>
            {
                ContentPage gotoPage;
                switch (e.Item.ToString())
                {
                    case "Home":
                        gotoPage = new HomePage();
                        break;

                    case "Second":
                        gotoPage = new HomePage();
                        break;
                    case "Third":
                        gotoPage = new HomePage();
                        break;
                    default:
                        gotoPage = new HomePage();
                        break;
                }

                Detail = new NavigationPage(gotoPage);
                ((ListView)sender).SelectedItem = null;
                this.IsPresented = false;

            };
            Detail = new NavigationPage(new HomePage());
        }
    }
}

In the main App.cs class

public class App : Application
    {
        public App()
        {
            // The root page of your application
            MainPage = new NavigationDrawer();

        }

It will look like this on android, but it works for windows etc ...