Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web.Extensions/ui/DeploymentSectionCache.cs

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+//------------------------------------------------------------------------------
+// <copyright file="DeploymentSectionCache.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+ 
+namespace System.Web.UI {
+    using System;
+    using System.Configuration;
+    using System.Security;
+    using System.Security.Permissions;
+    using System.Web.Configuration;
+
+    // DeploymentSection can only be defined in machine.config, so it is safe to cache statically in the application
+    internal sealed class DeploymentSectionCache : IDeploymentSection {
+        private static readonly DeploymentSectionCache _instance = new DeploymentSectionCache();
+        // Value is cached statically, because DeploymentSectionCache is a Singleton.
+        private bool? _retail;
+
+        private DeploymentSectionCache() {
+        }
+
+        public static DeploymentSectionCache Instance {
+            get {
+                return _instance;
+            }
+        }
+
+        public bool Retail {
+            get {
+                if (_retail == null) {
+                    _retail = GetRetailFromConfig();
+                }
+                return _retail.Value;
+            }
+        }
+
+        [
+        ConfigurationPermission(SecurityAction.Assert, Unrestricted = true),
+        SecuritySafeCritical()
+        ]
+        private static bool GetRetailFromConfig() {
+            DeploymentSection section = (DeploymentSection)WebConfigurationManager.GetSection("system.web/deployment");
+            return section.Retail;
+        }
+    }
+}