Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/LocationReferenceEnvironment.cs

@@ -0,0 +1,37 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.Activities
+{
+    using System;
+    using System.Activities.Hosting;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Linq.Expressions;
+    using System.Runtime;
+    using System.Activities.Validation;
+
+    [Fx.Tag.XamlVisible(false)]
+    public abstract class LocationReferenceEnvironment
+    {
+        protected LocationReferenceEnvironment()
+        {
+        }
+
+        public abstract Activity Root { get; }
+
+        public LocationReferenceEnvironment Parent
+        {
+            get;
+            protected set;
+        }
+
+        public abstract bool IsVisible(LocationReference locationReference);
+
+        public abstract bool TryGetLocationReference(string name, out LocationReference result);
+
+        public abstract IEnumerable<LocationReference> GetLocationReferences();               
+
+    }
+}