Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System/compmod/system/componentmodel/AsyncOperationManager.cs

@@ -0,0 +1,49 @@
+//------------------------------------------------------------------------------
+// <copyright file="AsyncOperationManager.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.ComponentModel
+{
+    using System.Collections;
+    using System.Threading;
+    using System.Diagnostics;
+    using System.Security.Permissions;
+
+    [HostProtection(SharedState = true)]
+    public static class AsyncOperationManager {
+        public static AsyncOperation CreateOperation(object userSuppliedState) {
+            return AsyncOperation.CreateOperation(userSuppliedState, SynchronizationContext);
+        }
+
+        /// <include file='doc\AsyncOperationManager.uex' path='docs/doc[@for="AsyncOperationManager.SynchronizationContext"]/*' />
+        [EditorBrowsable(EditorBrowsableState.Advanced)]
+        public static SynchronizationContext SynchronizationContext {
+            get {
+                if (SynchronizationContext.Current == null) {
+                    SynchronizationContext.SetSynchronizationContext(new SynchronizationContext());
+                }
+
+                return SynchronizationContext.Current;
+            }
+
+#if SILVERLIGHT
+            // a thread should set this to null  when it is done, else the context will never be disposed/GC'd
+            [SecurityCritical]
+            [FriendAccessAllowed]
+            internal set {
+                SynchronizationContext.SetSynchronizationContext(value);
+            }
+#else
+            // a thread should set this to null  when it is done, else the context will never be disposed/GC'd
+            [PermissionSetAttribute(SecurityAction.LinkDemand, Name="FullTrust")]
+            set {
+                SynchronizationContext.SetSynchronizationContext(value);
+            }
+#endif
+        }
+    }
+}
+
+