Added OnResponseCompleted to HttpResponse

src/Microsoft.AspNet.Http.Core/DefaultHttpResponse.cs

@@ -111,6 +111,11 @@ public override void OnSendingHeaders(Action<object> callback, object state)
             HttpResponseFeature.OnSendingHeaders(callback, state);
         }
 
+        public override void OnResponseCompleted(Action<object> callback, object state)
+        {
+            HttpResponseFeature.OnResponseCompleted(callback, state);
+        }
+
         public override void Redirect(string location, bool permanent)
         {
             if (permanent)

src/Microsoft.AspNet.Http.Core/HttpResponseFeature.cs

@@ -34,5 +34,10 @@ public void OnSendingHeaders(Action<object> callback, object state)
         {
             throw new NotSupportedException();
         }
+
+        public void OnResponseCompleted(Action<object> callback, object state)
+        {
+            throw new NotSupportedException();
+        }
     }
 }

src/Microsoft.AspNet.Http.Interfaces/IHttpResponseFeature.cs

@@ -15,5 +15,6 @@ public interface IHttpResponseFeature
         Stream Body { get; set; }
         bool HeadersSent { get; }
         void OnSendingHeaders(Action<object> callback, object state);
+        void OnResponseCompleted(Action<object> callback, object state);
     }
 }

src/Microsoft.AspNet.Http/HttpResponse.cs

@@ -27,6 +27,8 @@ public abstract class HttpResponse
 
         public abstract void OnSendingHeaders(Action<object> callback, object state);
 
+        public abstract void OnResponseCompleted(Action<object> callback, object state);
+
         public virtual void Redirect(string location)
         {
             Redirect(location, permanent: false);

src/Microsoft.AspNet.Owin/OwinFeatureCollection.cs

@@ -157,6 +157,11 @@ void IHttpResponseFeature.OnSendingHeaders(Action<object> callback, object state
             register(callback, state);
         }
 
+        void IHttpResponseFeature.OnResponseCompleted(Action<object> callback, object state)
+        {
+            throw new NotSupportedException();
+        }
+
         IPAddress IHttpConnectionFeature.RemoteIpAddress
         {
             get { return IPAddress.Parse(Prop<string>(OwinConstants.CommonKeys.RemoteIpAddress)); }