Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

external/rx/Rx/NET/Source/System.Reactive.Linq/Reactive/Internal/QueryServices.cs

@@ -0,0 +1,35 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+
+using System;
+using System.Reactive.PlatformServices;
+
+namespace System.Reactive.Linq
+{
+    internal static class QueryServices
+    {
+        private static Lazy<IQueryServices> s_services = new Lazy<IQueryServices>(Initialize);
+
+        public static T GetQueryImpl<T>(T defaultInstance)
+        {
+            return s_services.Value.Extend(defaultInstance);
+        }
+
+        private static IQueryServices Initialize()
+        {
+            return PlatformEnlightenmentProvider.Current.GetService<IQueryServices>() ?? new DefaultQueryServices();
+        }
+    }
+
+    internal interface IQueryServices
+    {
+        T Extend<T>(T baseImpl);
+    }
+
+    class DefaultQueryServices : IQueryServices
+    {
+        public T Extend<T>(T baseImpl)
+        {
+            return baseImpl;
+        }
+    }
+}