PaymentWebViewPage.xaml

CustomWebView.cs:

using System;
using Xamarin.Forms;

namespace CustomControls
{
	public class CustomWebView : WebView
	{ 
	}
}

PaymentWebViewPage.xaml:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage  xmlns:pages="clr-namespace:Views"
                            xmlns="http://xamarin.com/schemas/2014/forms"
                            xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
                            xmlns:customControls="clr-namespace:CustomControls" 
                            x:Name="PaymentWebViewPage"
                            x:Class="MyPlans.PaymentWebViewPage"> 
  <ContentPage.Content>
     <customControls:CustomWebView VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand"> 
     </customControls:CustomWebView> 
  </ContentPage.Content>
</ContentPage>