Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

external/aspnetwebstack/src/System.Web.Mvc/ControllerDescriptorCache.cs

@@ -0,0 +1,16 @@
+// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
+
+namespace System.Web.Mvc
+{
+    internal sealed class ControllerDescriptorCache : ReaderWriterCache<Type, ControllerDescriptor>
+    {
+        public ControllerDescriptorCache()
+        {
+        }
+
+        public ControllerDescriptor GetDescriptor(Type controllerType, Func<ControllerDescriptor> creator)
+        {
+            return FetchOrCreateItem(controllerType, creator);
+        }
+    }
+}