Async stream handling: Use interface instead of Func<Stream,Task>

No functional changes

MediaBrowser.Server.Implementations/HttpServer/AsyncStreamWriter.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using ServiceStack;
+using ServiceStack.Web;
+using MediaBrowser.Controller.Net;
+
+namespace MediaBrowser.Server.Implementations.HttpServer
+{
+    public class AsyncStreamWriter : IStreamWriter, IAsyncStreamWriter, IHasOptions
+    {
+        /// <summary>
+        /// Gets or sets the source stream.
+        /// </summary>
+        /// <value>The source stream.</value>
+        private IAsyncStreamSource _source;
+
+        public Action OnComplete { get; set; }
+        public Action OnError { get; set; }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AsyncStreamWriter" /> class.
+        /// </summary>
+        public AsyncStreamWriter(IAsyncStreamSource source)
+        {
+            _source = source;
+        }
+
+        public IDictionary<string, string> Options
+        {
+            get
+            {
+                var hasOptions = _source as IHasOptions;
+                if (hasOptions != null)
+                {
+                    return hasOptions.Options;
+                }
+
+                return new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            }
+        }
+
+        /// <summary>
+        /// Writes to.
+        /// </summary>
+        /// <param name="responseStream">The response stream.</param>
+        public void WriteTo(Stream responseStream)
+        {
+            var task = _source.WriteToAsync(responseStream);
+            Task.WaitAll(task);
+        }
+
+        public async Task WriteToAsync(Stream responseStream)
+        {
+            await _source.WriteToAsync(responseStream).ConfigureAwait(false);
+        }
+    }
+}