Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/class/System.Web.Mvc3/Mvc/ModelMetadataProviders.cs

@@ -0,0 +1,33 @@
+namespace System.Web.Mvc {
+    public class ModelMetadataProviders {
+        private ModelMetadataProvider _currentProvider;
+        private static ModelMetadataProviders _instance = new ModelMetadataProviders();
+        private IResolver<ModelMetadataProvider> _resolver;
+
+        internal ModelMetadataProviders(IResolver<ModelMetadataProvider> resolver = null) {
+            _resolver = resolver ?? new SingleServiceResolver<ModelMetadataProvider>(
+                () => _currentProvider,
+                new DataAnnotationsModelMetadataProvider(),
+                "ModelMetadataProviders.Current"
+            );
+        }
+
+        public static ModelMetadataProvider Current {
+            get {
+                return _instance.CurrentInternal;
+            }
+            set {
+                _instance.CurrentInternal = value;
+            }
+        }
+
+        internal ModelMetadataProvider CurrentInternal {
+            get {
+                return _resolver.Current;
+            }
+            set {
+                _currentProvider = value ?? new EmptyModelMetadataProvider();
+            }
+        }
+    }
+}