Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/ModelBinding/ValueProviderSourceAttribute.cs

@@ -0,0 +1,16 @@
+namespace System.Web.ModelBinding {
+    using System;
+
+    /// <summary>
+    /// This attribute is the base class for all the value provider attributes that can be specified on
+    /// method parameters to be able to get values from alternate sources like Form, QueryString, ViewState.
+    /// </summary>
+    public abstract class ValueProviderSourceAttribute : Attribute, IValueProviderSource, IModelNameProvider {
+
+        public abstract IValueProvider GetValueProvider(ModelBindingExecutionContext modelBindingExecutionContext);
+
+        public virtual string GetModelName() {
+            return null;
+        }
+    }
+}