Imported Upstream version 4.2.0.179

Former-commit-id: 4610231f55806d2a05ed69e5ff3faa7336cc1479

external/referencesource/System.Configuration/System/Configuration/Internal/StreamChangeCallback.cs

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+//------------------------------------------------------------------------------
+// <copyright file="StreamChangeCallback.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+using System;
+using System.IO;
+using System.Security;
+using System.Collections.Specialized;
+using System.Configuration;
+using ClassConfiguration=System.Configuration.Configuration;
+
+//
+// This file contains most of the interfaces that allow System.Web, Venus, and 
+// Whitehorse to customize configuration in some way.
+//
+// The goal of the design of customization is to only require other MS assemblies
+// to create an instance of an internal object via Activator.CreateInstance(), and then
+// use these objects through *public* System.Configuration.Internal interfaces. 
+// We do not want extenders to have to use reflection to call a method - it is slow,
+// not typesafe, and more difficult to promote correct use of the internal object.
+//
+namespace System.Configuration.Internal {
+
+    // Callback for hosts to call when a stream that is being monitored has changed.
+    public delegate void StreamChangeCallback(string streamName);
+}