added cors bypass for RSS parser sample

Author: Xiaoy312

Microsoft.Toolkit.Uwp.SampleApp.Shared/SamplePages/RssParser/RssParserPage.xaml.cs

@@ -1,10 +1,11 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
-
 using System;
 using System.Collections.ObjectModel;
 using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.Toolkit.Parsers.Rss;
 using Windows.System;
 using Windows.UI.Xaml.Controls;
@@ -18,7 +19,7 @@ public sealed partial class RssParserPage : Page
         public RssParserPage()
         {
             this.InitializeComponent();
-			Loaded += (s, e) => ParseRSS();
+            Loaded += (s, e) => ParseRSS();
         }
 
         public string Url { get; set; } = "https://visualstudiomagazine.com/rss-feeds/news.aspx";
@@ -28,7 +29,11 @@ public async void ParseRSS()
             string feed = null;
             RSSFeed.Clear();
 
+#if __WASM__
+            using (var client = new HttpClient(new CorsBypassHandler()))
+#else
             using (var client = new HttpClient())
+#endif
             {
                 try
                 {
@@ -66,5 +71,24 @@ private async void RSSList_SelectionChanged(object sender, SelectionChangedEvent
 
             RSSList.SelectedItem = null;
         }
+
+#if __WASM__
+        public class CorsBypassHandler : DelegatingHandler
+        {
+            public CorsBypassHandler()
+            {
+                InnerHandler = new HttpClientHandler();
+            }
+
+            protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+            {
+                var builder = new UriBuilder(request.RequestUri);
+                builder.Host = "cors-anywhere.herokuapp.com";
+                builder.Path = request.RequestUri.Host + builder.Path;
+
+                return base.SendAsync(new HttpRequestMessage(request.Method, builder.Uri), cancellationToken);
+            }
+        }
+#endif
     }
 }