Put migration mapping changes back in

Author: alvinashcraft

hub/apps/windows-app-sdk/migrate-to-windows-app-sdk/api-mapping-table.md

@@ -18,6 +18,7 @@ There are differences in the names of namespaces and classes (including UI contr
 | UWP | Windows App SDK |
 | - | - |
 | (**Windows.ApplicationModel.Activation**) [**LaunchActivatedEventArgs**](/uwp/api/windows.applicationmodel.activation.launchactivatedeventargs) class | (**Microsoft.UI.Xaml**) [**LaunchActivatedEventArgs**](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.launchactivatedeventargs) class; for example, in **App.OnLaunched**. |
+| (**Windows.ApplicationModel.Background**) [**BackgroundTaskBuilder**](/uwp/api/windows.applicationmodel.background.backgroundtaskbuilder) class | (**Microsoft.Windows.ApplicationModel.Background**) [**BackgroundTaskBuilder**](/windows/windows-app-sdk/api/winrt/microsoft.windows.applicationmodel.background.backgroundtaskbuilder) class. See [Using background tasks in Windows apps](../applifecycle/background-tasks.md). |
 | (**Windows.ApplicationModel.Core**) [**CoreApplication.CreateNewView**](/uwp/api/windows.applicationmodel.core.coreapplication.createnewview) method | (**Microsoft.UI.Windowing**) [**AppWindow.Create**](/windows/windows-app-sdk/api/winrt/microsoft.ui.windowing.appwindow.create) method |
 | (**Windows.ApplicationModel.Core**) [**CoreApplicationViewTitleBar**](/uwp/api/windows.applicationmodel.core.coreapplicationviewtitlebar) class | (**Microsoft.UI.Windowing**) [**AppWindowTitleBar**](/windows/windows-app-sdk/api/winrt/microsoft.ui.windowing.appwindowtitlebar) class |
 | (**Windows.ApplicationModel.Core**) [**CoreApplicationViewTitleBar.ExtendViewIntoTitleBar**](/uwp/api/windows.applicationmodel.core.coreapplicationviewtitlebar.extendviewintotitlebar) property | (**Microsoft.UI.Windowing**) [**AppWindowTitleBar.ExtendsContentIntoTitleBar**](/windows/windows-app-sdk/api/winrt/microsoft.ui.windowing.appwindowtitlebar.extendscontentintotitlebar) property. The platform continues to draw the **Minimize**/**Maximize**/**Close** buttons for you, and reports the occlusion information. |

hub/apps/windows-app-sdk/migrate-to-windows-app-sdk/feature-mapping-table.md

@@ -17,7 +17,7 @@ This topic compares major feature areas in the different forms in which they app
 | Container | App container:<br/>- security = LowIL<br/>- file system access is brokered<br/>- no registry access | MSIX Container:<br/>- security = MediumIL<br/>- file system access same as user, AppData writes virtualized<br/>- HKCU registry writes virtualized | Moving to a higher integrity level with the Windows App SDK allows your app to have greater functionality. However, be aware of virtualization if you want to expand the capabilities of your migrated application to write to HKCU or AppData. |
 | Activation and instancing | Package identity + CoreApplication activation, single-instanced by default | Package identity, Main/WinMain + Windows App SDK activation, multi-instanced by default | Ensure your application can handle multi-instance behavior, or use [**AppInstance**](/windows/windows-app-sdk/api/winrt/microsoft.windows.applifecycle.appinstance) to manage your instances. |
 | Lifecycle-managed | Suspend/resume | Power/State notifications |  You can use Power/State change notifications to reduce system load. |
-| Background tasks | InProc and OOP background tasks | Inproc COM and OOP background tasks | You can continue to use your OOP background tasks. If the app requires communication to your main process, then evaluate your IPC mechanism, as the OOP background task is running in LowIL, and your Windows App SDK main process is running in MediumIL.<br/><br/>Any inproc background tasks need to be migrated to COM background tasks&mdash;see [Create and register a winmain COM background task](/windows/uwp/launch-resume/create-and-register-a-winmain-background-task).<br/><br/>For C# OOP background tasks, see [Author Windows Runtime components with C#/WinRT](../../develop/platform/csharp-winrt/authoring.md) and the [Background task sample](https://github.com/microsoft/CsWinRT/tree/master/src/Samples/BgTaskComponent). |
+| Background tasks | InProc and OOP background tasks | Full trust COM background task implementation | For more info, see [Background task migration strategy](guides/background-task-migration-strategy.md). |
 | Windowing | CoreWindow, AppWindow (preview) | HWND, AppWindow v2 | Windowing behavior has significantly changed in Windows App SDK. See [Windowing functionality migration](guides/windowing.md). |
 | Messaging | CoreDispatcher and DispatcherQueue | DispatcherQueue, WndProc | [**DispatcherQueue**](/windows/windows-app-sdk/api/winrt/microsoft.ui.dispatching.dispatcherqueue) supports Win32 apps. For additional details on moving from CoreDispatcher to DispatcherQueue see [Threading functionality migration](guides/threading.md). |
 | UI Platform| System XAML, WebView, DirectX, and others | WinUI 3, Webview2, DirectX, and others | For more info, see [WinUI migration](guides/winui3.md). |