Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/Debugger/Symbol/DebugSymbol.cs

@@ -0,0 +1,41 @@
+//----------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//----------------------------------------------------------------
+namespace System.Activities.Debugger.Symbol
+{
+    using System;
+    using System.Diagnostics.CodeAnalysis;
+    using System.Xaml;
+    using System.Runtime;
+
+
+    [Fx.Tag.XamlVisible(false)]
+    public static class DebugSymbol
+    {
+        static Type attachingTypeName = typeof(DebugSymbol);
+
+        [SuppressMessage(FxCop.Category.Security, FxCop.Rule.DoNotDeclareReadOnlyMutableReferenceTypes)]
+        public static readonly AttachableMemberIdentifier SymbolName = new AttachableMemberIdentifier(attachingTypeName, "Symbol");
+
+
+        [Fx.Tag.InheritThrows(From = "SetProperty", FromDeclaringType = typeof(AttachablePropertyServices))]
+        public static void SetSymbol(object instance, object value)
+        {
+            AttachablePropertyServices.SetProperty(instance, SymbolName, value);
+        }
+
+        [Fx.Tag.InheritThrows(From = "TryGetProperty", FromDeclaringType = typeof(AttachablePropertyServices))]
+        public static object GetSymbol(object instance)
+        {
+            string value;
+            if (AttachablePropertyServices.TryGetProperty(instance, SymbolName, out value))
+            {
+                return value;
+            }
+            else
+            {
+                return string.Empty;
+            }
+        }
+    }
+}