Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.IdentityModel/System/IdentityModel/SignatureTargetIdManager.cs

@@ -0,0 +1,23 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace System.IdentityModel
+{
+    using System.Xml;
+
+    abstract class SignatureTargetIdManager
+    {
+        protected SignatureTargetIdManager()
+        {
+        }
+
+        public abstract string DefaultIdNamespacePrefix { get; }
+
+        public abstract string DefaultIdNamespaceUri { get; }
+
+        public abstract string ExtractId(XmlDictionaryReader reader);
+
+        public abstract void WriteIdAttribute(XmlDictionaryWriter writer, string id);
+    }
+}