Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/UI/ErrorFormatterPage.cs

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+//------------------------------------------------------------------------------
+// <copyright file="ErrorFormatterPage.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+/*
+ * This is a page class that is used for adaptive error formatting for mobile
+ * devices.
+ *
+ * NOTE: We explicitly override the state management methods because if the
+ *       normal page class is used, an exception is thrown for mobile devices.
+ *       For example, WmlPageAdapter uses SessionPageStatePersister
+ *       for persisting view state.  SessionPageStatePersister requires
+ *       Context.Session to be available.  Otherwise, it would throw in the
+ *       constructor.  However, when an error occurred, Context.Session is
+ *       removed by SessionStateModule before the error is being formatted and
+ *       rendered.  Hence the methods are overridden below and ignored to avoid
+ *       the exception since there is no need to persist any view state for the
+ *       adaptive error page which is created dynamically during error handling.
+ *
+ * Copyright (c) 2003 Microsoft Corporation
+ */
+
+namespace System.Web.UI {
+    using System.Diagnostics.CodeAnalysis;
+
+    [SuppressMessage("Microsoft.MSInternal", "CA910:AlwaysSetViewStateUserKeyToUniqueValue",
+        Justification = "This page does not allow access to sensitive information.")]
+    internal sealed class ErrorFormatterPage : Page {
+        protected internal override void SavePageStateToPersistenceMedium(Object viewState) {
+            // Override and ignore. No need to save view state for this page.
+        }
+
+        protected internal override Object LoadPageStateFromPersistenceMedium() {
+            // Override and ignore. No view state to load for this page.
+            return null;
+        }
+    }
+}