Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Web/ModelBinding/ViewStateValueProvider.cs

@@ -0,0 +1,24 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Web.UI;
+
+namespace System.Web.ModelBinding {
+    /// <summary>
+    /// Provides a value from Page's ViewState.
+    /// </summary>
+    public sealed class ViewStateValueProvider : SimpleValueProvider {
+
+        [SuppressMessage("Microsoft.Globalization", "CA1304:SpecifyCultureInfo", MessageId = "System.Web.ModelBinding.SimpleValueProvider.#ctor(System.Web.ModelBinding.ModelBindingExecutionContext)",
+            Justification = "SimpleValueProvider Constructor specifies the CultureInfo")]
+        public ViewStateValueProvider(ModelBindingExecutionContext modelBindingExecutionContext)
+            : base(modelBindingExecutionContext) {
+        }
+
+        protected override object FetchValue(string key) {
+            StateBag pageViewState = ModelBindingExecutionContext.GetService<StateBag>();
+            if (pageViewState != null) {
+                return pageViewState[key];
+            }
+            return null;
+        }
+    }
+}