Merge "Add WindowDecorViewHost and WindowDecorViewHostSupplier" into main

14 files changed, 730 insertions, 322 deletions

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
index 7054c17cfeb0..8c7dcf295319 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
@@ -18,6 +18,7 @@ package com.android.wm.shell.dagger;
 
 import static com.android.wm.shell.shared.desktopmode.DesktopModeFlags.ENABLE_DESKTOP_WINDOWING_TASK_LIMIT;
 
+import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.app.KeyguardManager;
 import android.content.Context;
@@ -114,6 +115,8 @@ import com.android.wm.shell.unfold.qualifier.UnfoldTransition;
 import com.android.wm.shell.windowdecor.CaptionWindowDecorViewModel;
 import com.android.wm.shell.windowdecor.DesktopModeWindowDecorViewModel;
 import com.android.wm.shell.windowdecor.WindowDecorViewModel;
+import com.android.wm.shell.windowdecor.viewhost.DefaultWindowDecorViewHostSupplier;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 import dagger.Binds;
 import dagger.Lazy;
@@ -244,7 +247,8 @@ public abstract class WMShellModule {
             AssistContentRequester assistContentRequester,
             MultiInstanceHelper multiInstanceHelper,
             Optional<DesktopTasksLimiter> desktopTasksLimiter,
-            Optional<DesktopActivityOrientationChangeHandler> desktopActivityOrientationHandler) {
+            Optional<DesktopActivityOrientationChangeHandler> desktopActivityOrientationHandler,
+            WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
         if (DesktopModeStatus.canEnterDesktopMode(context)) {
             return new DesktopModeWindowDecorViewModel(
                     context,
@@ -268,7 +272,8 @@ public abstract class WMShellModule {
                     assistContentRequester,
                     multiInstanceHelper,
                     desktopTasksLimiter,
-                    desktopActivityOrientationHandler);
+                    desktopActivityOrientationHandler,
+                    windowDecorViewHostSupplier);
         }
         return new CaptionWindowDecorViewModel(
                 context,
@@ -282,7 +287,8 @@ public abstract class WMShellModule {
                 displayController,
                 rootTaskDisplayAreaOrganizer,
                 syncQueue,
-                transitions);
+                transitions,
+                windowDecorViewHostSupplier);
     }
 
     @WMSingleton
@@ -371,6 +377,13 @@ public abstract class WMShellModule {
                 context, shellInit, transitions, windowDecorViewModel);
     }
 
+    @WMSingleton
+    @Provides
+    static WindowDecorViewHostSupplier provideWindowDecorViewHostSupplier(
+            @ShellMainThread @NonNull CoroutineScope mainScope) {
+        return new DefaultWindowDecorViewHostSupplier(mainScope);
+    }
+
     //
     // One handed mode
     //
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java
index 11976aed9315..015139519f1f 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java
@@ -62,6 +62,7 @@ import com.android.wm.shell.splitscreen.SplitScreenController;
 import com.android.wm.shell.sysui.ShellInit;
 import com.android.wm.shell.transition.Transitions;
 import com.android.wm.shell.windowdecor.extension.TaskInfoKt;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 /**
  * View model for the window decoration with a caption and shadows. Works with
@@ -83,6 +84,7 @@ public class CaptionWindowDecorViewModel implements WindowDecorViewModel {
     private final Transitions mTransitions;
     private final Region mExclusionRegion = Region.obtain();
     private final InputManager mInputManager;
+    private final WindowDecorViewHostSupplier mWindowDecorViewHostSupplier;
     private TaskOperations mTaskOperations;
 
     /**
@@ -120,7 +122,8 @@ public class CaptionWindowDecorViewModel implements WindowDecorViewModel {
             DisplayController displayController,
             RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer,
             SyncTransactionQueue syncQueue,
-            Transitions transitions) {
+            Transitions transitions,
+            WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
         mContext = context;
         mMainExecutor = shellExecutor;
         mMainHandler = mainHandler;
@@ -132,6 +135,7 @@ public class CaptionWindowDecorViewModel implements WindowDecorViewModel {
         mRootTaskDisplayAreaOrganizer = rootTaskDisplayAreaOrganizer;
         mSyncQueue = syncQueue;
         mTransitions = transitions;
+        mWindowDecorViewHostSupplier = windowDecorViewHostSupplier;
         if (!Transitions.ENABLE_SHELL_TRANSITIONS) {
             mTaskOperations = new TaskOperations(null, mContext, mSyncQueue);
         }
@@ -295,7 +299,8 @@ public class CaptionWindowDecorViewModel implements WindowDecorViewModel {
                         mMainHandler,
                         mBgExecutor,
                         mMainChoreographer,
-                        mSyncQueue);
+                        mSyncQueue,
+                        mWindowDecorViewHostSupplier);
         mWindowDecorByTaskId.put(taskInfo.taskId, windowDecoration);
 
         final FluidResizeTaskPositioner taskPositioner =
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java
index 349ee0b1fcda..46fe68f44bed 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java
@@ -56,6 +56,7 @@ import com.android.wm.shell.common.ShellExecutor;
 import com.android.wm.shell.common.SyncTransactionQueue;
 import com.android.wm.shell.shared.annotations.ShellBackgroundThread;
 import com.android.wm.shell.windowdecor.extension.TaskInfoKt;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 /**
  * Defines visuals and behaviors of a window decoration of a caption bar and shadows. It works with
@@ -88,8 +89,10 @@ public class CaptionWindowDecoration extends WindowDecoration<WindowDecorLinearL
             Handler handler,
             @ShellBackgroundThread ShellExecutor bgExecutor,
             Choreographer choreographer,
-            SyncTransactionQueue syncQueue) {
-        super(context, userContext, displayController, taskOrganizer, taskInfo, taskSurface);
+            SyncTransactionQueue syncQueue,
+            WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
+        super(context, userContext, displayController, taskOrganizer, taskInfo, taskSurface,
+                windowDecorViewHostSupplier);
         mHandler = handler;
         mBgExecutor = bgExecutor;
         mChoreographer = choreographer;
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java
index 0f8bd2866fa8..a0047da46d60 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java
@@ -122,6 +122,7 @@ import com.android.wm.shell.windowdecor.DesktopModeWindowDecoration.ExclusionReg
 import com.android.wm.shell.windowdecor.extension.InsetsStateKt;
 import com.android.wm.shell.windowdecor.extension.TaskInfoKt;
 import com.android.wm.shell.windowdecor.viewholder.AppHeaderViewHolder;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 import kotlin.Unit;
 
@@ -155,6 +156,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
     private final InteractionJankMonitor mInteractionJankMonitor;
     private final MultiInstanceHelper mMultiInstanceHelper;
     private final Optional<DesktopTasksLimiter> mDesktopTasksLimiter;
+    private final WindowDecorViewHostSupplier mWindowDecorViewHostSupplier;
     private boolean mTransitionDragActive;
 
     private SparseArray<EventReceiver> mEventReceiversByDisplay = new SparseArray<>();
@@ -223,8 +225,8 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             AssistContentRequester assistContentRequester,
             MultiInstanceHelper multiInstanceHelper,
             Optional<DesktopTasksLimiter> desktopTasksLimiter,
-            Optional<DesktopActivityOrientationChangeHandler> activityOrientationChangeHandler
-    ) {
+            Optional<DesktopActivityOrientationChangeHandler> activityOrientationChangeHandler,
+            WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
         this(
                 context,
                 shellExecutor,
@@ -244,6 +246,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
                 genericLinksParser,
                 assistContentRequester,
                 multiInstanceHelper,
+                windowDecorViewHostSupplier,
                 new DesktopModeWindowDecoration.Factory(),
                 new InputMonitorFactory(),
                 SurfaceControl.Transaction::new,
@@ -275,6 +278,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             AppToWebGenericLinksParser genericLinksParser,
             AssistContentRequester assistContentRequester,
             MultiInstanceHelper multiInstanceHelper,
+            WindowDecorViewHostSupplier windowDecorViewHostSupplier,
             DesktopModeWindowDecoration.Factory desktopModeWindowDecorFactory,
             InputMonitorFactory inputMonitorFactory,
             Supplier<SurfaceControl.Transaction> transactionFactory,
@@ -300,6 +304,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
         mMultiInstanceHelper = multiInstanceHelper;
         mShellCommandHandler = shellCommandHandler;
         mWindowManager = windowManager;
+        mWindowDecorViewHostSupplier = windowDecorViewHostSupplier;
         mDesktopModeWindowDecorFactory = desktopModeWindowDecorFactory;
         mInputMonitorFactory = inputMonitorFactory;
         mTransactionFactory = transactionFactory;
@@ -1284,7 +1289,8 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
                         mRootTaskDisplayAreaOrganizer,
                         mGenericLinksParser,
                         mAssistContentRequester,
-                        mMultiInstanceHelper);
+                        mMultiInstanceHelper,
+                        mWindowDecorViewHostSupplier);
         mWindowDecorByTaskId.put(taskInfo.taskId, windowDecoration);
 
         final TaskPositioner taskPositioner = mTaskPositionerFactory.create(
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java
index 142be91fe942..1409d3011395 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java
@@ -35,7 +35,6 @@ import static com.android.wm.shell.windowdecor.DragResizeWindowGeometry.getResiz
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
-import android.annotation.SuppressLint;
 import android.app.ActivityManager;
 import android.app.WindowConfiguration.WindowingMode;
 import android.app.assist.AssistContent;
@@ -92,6 +91,7 @@ import com.android.wm.shell.windowdecor.extension.TaskInfoKt;
 import com.android.wm.shell.windowdecor.viewholder.AppHandleViewHolder;
 import com.android.wm.shell.windowdecor.viewholder.AppHeaderViewHolder;
 import com.android.wm.shell.windowdecor.viewholder.WindowDecorationViewHolder;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 import kotlin.Unit;
 import kotlin.jvm.functions.Function0;
@@ -134,12 +134,9 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
     private DragPositioningCallback mDragPositioningCallback;
     private DragResizeInputListener mDragResizeListener;
     private DragDetector mDragDetector;
-    private Runnable mCurrentViewHostRunnable = null;
     private RelayoutParams mRelayoutParams = new RelayoutParams();
     private final WindowDecoration.RelayoutResult<WindowDecorLinearLayout> mResult =
             new WindowDecoration.RelayoutResult<>();
-    private final Runnable mViewHostRunnable =
-            () -> updateViewHost(mRelayoutParams, null /* onDrawTransaction */, mResult);
 
     private final Point mPositionInParent = new Point();
     private HandleMenu mHandleMenu;
@@ -190,14 +187,16 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
             RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer,
             AppToWebGenericLinksParser genericLinksParser,
             AssistContentRequester assistContentRequester,
-            MultiInstanceHelper multiInstanceHelper) {
+            MultiInstanceHelper multiInstanceHelper,
+            WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
         this (context, userContext, displayController, splitScreenController, taskOrganizer,
                 taskInfo, taskSurface, handler, bgExecutor, choreographer, syncQueue,
                 rootTaskDisplayAreaOrganizer, genericLinksParser, assistContentRequester,
                 SurfaceControl.Builder::new, SurfaceControl.Transaction::new,
                 WindowContainerTransaction::new, SurfaceControl::new, new WindowManagerWrapper(
                         context.getSystemService(WindowManager.class)),
-                new SurfaceControlViewHostFactory() {}, DefaultMaximizeMenuFactory.INSTANCE,
+                new SurfaceControlViewHostFactory() {}, windowDecorViewHostSupplier,
+                DefaultMaximizeMenuFactory.INSTANCE,
                 DefaultHandleMenuFactory.INSTANCE, multiInstanceHelper);
     }
 
@@ -222,13 +221,14 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
             Supplier<SurfaceControl> surfaceControlSupplier,
             WindowManagerWrapper windowManagerWrapper,
             SurfaceControlViewHostFactory surfaceControlViewHostFactory,
+            WindowDecorViewHostSupplier windowDecorViewHostSupplier,
             MaximizeMenuFactory maximizeMenuFactory,
             HandleMenuFactory handleMenuFactory,
             MultiInstanceHelper multiInstanceHelper) {
         super(context, userContext, displayController, taskOrganizer, taskInfo, taskSurface,
                 surfaceControlBuilderSupplier, surfaceControlTransactionSupplier,
                 windowContainerTransactionSupplier, surfaceControlSupplier,
-                surfaceControlViewHostFactory);
+                surfaceControlViewHostFactory, windowDecorViewHostSupplier);
         mSplitScreenController = splitScreenController;
         mHandler = handler;
         mBgExecutor = bgExecutor;
@@ -337,73 +337,6 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
             SurfaceControl.Transaction startT, SurfaceControl.Transaction finishT,
             boolean applyStartTransactionOnDraw, boolean shouldSetTaskPositionAndCrop) {
         Trace.beginSection("DesktopModeWindowDecoration#relayout");
-        if (taskInfo.isFreeform()) {
-            // The Task is in Freeform mode -> show its header in sync since it's an integral part
-            // of the window itself - a delayed header might cause bad UX.
-            relayoutInSync(taskInfo, startT, finishT, applyStartTransactionOnDraw,
-                    shouldSetTaskPositionAndCrop);
-        } else {
-            // The Task is outside Freeform mode -> allow the handle view to be delayed since the
-            // handle is just a small addition to the window.
-            relayoutWithDelayedViewHost(taskInfo, startT, finishT, applyStartTransactionOnDraw,
-                    shouldSetTaskPositionAndCrop);
-        }
-        Trace.endSection();
-    }
-
-    /** Run the whole relayout phase immediately without delay. */
-    private void relayoutInSync(ActivityManager.RunningTaskInfo taskInfo,
-            SurfaceControl.Transaction startT, SurfaceControl.Transaction finishT,
-            boolean applyStartTransactionOnDraw, boolean shouldSetTaskPositionAndCrop) {
-        // Clear the current ViewHost runnable as we will update the ViewHost here
-        clearCurrentViewHostRunnable();
-        updateRelayoutParamsAndSurfaces(taskInfo, startT, finishT, applyStartTransactionOnDraw,
-                shouldSetTaskPositionAndCrop);
-        if (mResult.mRootView != null) {
-            updateViewHost(mRelayoutParams, startT, mResult);
-        }
-    }
-
-    /**
-     * Clear the current ViewHost runnable - to ensure it doesn't run once relayout params have been
-     * updated.
-     */
-    private void clearCurrentViewHostRunnable() {
-        if (mCurrentViewHostRunnable != null) {
-            mHandler.removeCallbacks(mCurrentViewHostRunnable);
-            mCurrentViewHostRunnable = null;
-        }
-    }
-
-    /**
-     * Relayout the window decoration but repost some of the work, to unblock the current callstack.
-     */
-    private void relayoutWithDelayedViewHost(ActivityManager.RunningTaskInfo taskInfo,
-            SurfaceControl.Transaction startT, SurfaceControl.Transaction finishT,
-            boolean applyStartTransactionOnDraw, boolean shouldSetTaskPositionAndCrop) {
-        if (applyStartTransactionOnDraw) {
-            throw new IllegalArgumentException(
-                    "We cannot both sync viewhost ondraw and delay viewhost creation.");
-        }
-        // Clear the current ViewHost runnable as we will update the ViewHost here
-        clearCurrentViewHostRunnable();
-        updateRelayoutParamsAndSurfaces(taskInfo, startT, finishT,
-                false /* applyStartTransactionOnDraw */, shouldSetTaskPositionAndCrop);
-        if (mResult.mRootView == null) {
-            // This means something blocks the window decor from showing, e.g. the task is hidden.
-            // Nothing is set up in this case including the decoration surface.
-            return;
-        }
-        // Store the current runnable so it can be removed if we start a new relayout.
-        mCurrentViewHostRunnable = mViewHostRunnable;
-        mHandler.post(mCurrentViewHostRunnable);
-    }
-
-    @SuppressLint("MissingPermission")
-    private void updateRelayoutParamsAndSurfaces(ActivityManager.RunningTaskInfo taskInfo,
-            SurfaceControl.Transaction startT, SurfaceControl.Transaction finishT,
-            boolean applyStartTransactionOnDraw, boolean shouldSetTaskPositionAndCrop) {
-        Trace.beginSection("DesktopModeWindowDecoration#updateRelayoutParamsAndSurfaces");
 
         if (Flags.enableDesktopWindowingAppToWeb()) {
             setCapturedLink(taskInfo.capturedLink, taskInfo.capturedLinkTimestamp);
@@ -420,8 +353,8 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
         final SurfaceControl oldDecorationSurface = mDecorationContainerSurface;
         final WindowContainerTransaction wct = new WindowContainerTransaction();
 
-        Trace.beginSection("DesktopModeWindowDecoration#relayout-updateViewsAndSurfaces");
-        updateViewsAndSurfaces(mRelayoutParams, startT, finishT, wct, oldRootView, mResult);
+        Trace.beginSection("DesktopModeWindowDecoration#relayout-inner");
+        relayout(mRelayoutParams, startT, finishT, wct, oldRootView, mResult);
         Trace.endSection();
         // After this line, mTaskInfo is up-to-date and should be used instead of taskInfo
 
@@ -433,7 +366,7 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
             // This means something blocks the window decor from showing, e.g. the task is hidden.
             // Nothing is set up in this case including the decoration surface.
             disposeStatusBarInputLayer();
-            Trace.endSection(); // DesktopModeWindowDecoration#updateRelayoutParamsAndSurfaces
+            Trace.endSection(); // DesktopModeWindowDecoration#relayout
             return;
         }
 
@@ -441,12 +374,12 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
             disposeStatusBarInputLayer();
             mWindowDecorViewHolder = createViewHolder();
         }
-        Trace.beginSection("DesktopModeWindowDecoration#relayout-binding");
 
         final Point position = new Point();
         if (isAppHandle(mWindowDecorViewHolder)) {
             position.set(determineHandlePosition());
         }
+        Trace.beginSection("DesktopModeWindowDecoration#relayout-bindData");
         mWindowDecorViewHolder.bindData(mTaskInfo,
                 position,
                 mResult.mCaptionWidth,
@@ -460,7 +393,7 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
         }
         updateDragResizeListener(oldDecorationSurface);
         updateMaximizeMenu(startT);
-        Trace.endSection(); // DesktopModeWindowDecoration#updateRelayoutParamsAndSurfaces
+        Trace.endSection(); // DesktopModeWindowDecoration#relayout
     }
 
     private boolean isCaptionVisible() {
@@ -638,6 +571,10 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
         relayoutParams.mLayoutResId = captionLayoutId;
         relayoutParams.mCaptionHeightId = getCaptionHeightIdStatic(taskInfo.getWindowingMode());
         relayoutParams.mCaptionWidthId = getCaptionWidthId(relayoutParams.mLayoutResId);
+        // Allow the handle view to be delayed since the handle is just a small addition to the
+        // window, whereas the header cannot be delayed because it is expected to be visible from
+        // the first frame.
+        relayoutParams.mAsyncViewHost = isAppHandle;
 
         if (isAppHeader) {
             if (TaskInfoKt.isTransparentCaptionBarAppearance(taskInfo)) {
@@ -1253,7 +1190,6 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
         mExclusionRegionListener.onExclusionRegionDismissed(mTaskInfo.taskId);
         disposeResizeVeil();
         disposeStatusBarInputLayer();
-        clearCurrentViewHostRunnable();
         super.close();
     }
 
@@ -1364,7 +1300,8 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
                 RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer,
                 AppToWebGenericLinksParser genericLinksParser,
                 AssistContentRequester assistContentRequester,
-                MultiInstanceHelper multiInstanceHelper) {
+                MultiInstanceHelper multiInstanceHelper,
+                WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
             return new DesktopModeWindowDecoration(
                     context,
                     userContext,
@@ -1380,7 +1317,8 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
                     rootTaskDisplayAreaOrganizer,
                     genericLinksParser,
                     assistContentRequester,
-                    multiInstanceHelper);
+                    multiInstanceHelper,
+                    windowDecorViewHostSupplier);
         }
     }
 
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
index c1a55b48a02a..369484558325 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
@@ -62,6 +62,8 @@ import com.android.wm.shell.shared.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.windowdecor.WindowDecoration.RelayoutParams.OccludingCaptionElement;
 import com.android.wm.shell.windowdecor.additionalviewcontainer.AdditionalViewHostViewContainer;
 import com.android.wm.shell.windowdecor.extension.InsetsStateKt;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHost;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -116,6 +118,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
     final Supplier<SurfaceControl.Transaction> mSurfaceControlTransactionSupplier;
     final Supplier<WindowContainerTransaction> mWindowContainerTransactionSupplier;
     final SurfaceControlViewHostFactory mSurfaceControlViewHostFactory;
+    @NonNull private final WindowDecorViewHostSupplier mWindowDecorViewHostSupplier;
     private final DisplayController.OnDisplaysChangedListener mOnDisplaysChangedListener =
             new DisplayController.OnDisplaysChangedListener() {
                 @Override
@@ -137,9 +140,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
     Context mDecorWindowContext;
     SurfaceControl mDecorationContainerSurface;
 
-    SurfaceControl mCaptionContainerSurface;
-    private WindowlessWindowManager mCaptionWindowManager;
-    private SurfaceControlViewHost mViewHost;
+    private WindowDecorViewHost mDecorViewHost;
     private Configuration mWindowDecorConfig;
     TaskDragResizer mTaskDragResizer;
     boolean mIsCaptionVisible;
@@ -158,11 +159,13 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
             DisplayController displayController,
             ShellTaskOrganizer taskOrganizer,
             RunningTaskInfo taskInfo,
-            SurfaceControl taskSurface) {
+            SurfaceControl taskSurface,
+            @NonNull WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
         this(context, userContext, displayController, taskOrganizer, taskInfo, taskSurface,
                 SurfaceControl.Builder::new, SurfaceControl.Transaction::new,
                 WindowContainerTransaction::new, SurfaceControl::new,
-                new SurfaceControlViewHostFactory() {});
+                new SurfaceControlViewHostFactory() {},
+                windowDecorViewHostSupplier);
     }
 
     WindowDecoration(
@@ -176,7 +179,8 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
             Supplier<SurfaceControl.Transaction> surfaceControlTransactionSupplier,
             Supplier<WindowContainerTransaction> windowContainerTransactionSupplier,
             Supplier<SurfaceControl> surfaceControlSupplier,
-            SurfaceControlViewHostFactory surfaceControlViewHostFactory) {
+            SurfaceControlViewHostFactory surfaceControlViewHostFactory,
+            @NonNull WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
         mContext = context;
         mUserContext = userContext;
         mDisplayController = displayController;
@@ -187,6 +191,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
         mSurfaceControlTransactionSupplier = surfaceControlTransactionSupplier;
         mWindowContainerTransactionSupplier = windowContainerTransactionSupplier;
         mSurfaceControlViewHostFactory = surfaceControlViewHostFactory;
+        mWindowDecorViewHostSupplier = windowDecorViewHostSupplier;
         mDisplay = mDisplayController.getDisplay(mTaskInfo.displayId);
         final InsetsState insetsState = mDisplayController.getInsetsState(mTaskInfo.displayId);
         mIsStatusBarVisible = insetsState != null
@@ -212,15 +217,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
     void relayout(RelayoutParams params, SurfaceControl.Transaction startT,
             SurfaceControl.Transaction finishT, WindowContainerTransaction wct, T rootView,
             RelayoutResult<T> outResult) {
-        updateViewsAndSurfaces(params, startT, finishT, wct, rootView, outResult);
-        if (outResult.mRootView != null) {
-            updateViewHost(params, startT, outResult);
-        }
-    }
-
-    protected void updateViewsAndSurfaces(RelayoutParams params,
-            SurfaceControl.Transaction startT, SurfaceControl.Transaction finishT,
-            WindowContainerTransaction wct, T rootView, RelayoutResult<T> outResult) {
+        Trace.beginSection("WindowDecoration#relayout");
         outResult.reset();
         if (params.mRunningTaskInfo != null) {
             mTaskInfo = params.mRunningTaskInfo;
@@ -231,17 +228,21 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
         if (!mTaskInfo.isVisible) {
             releaseViews(wct);
             finishT.hide(mTaskSurface);
+            Trace.endSection(); // WindowDecoration#relayout
             return;
         }
-
+        Trace.beginSection("WindowDecoration#relayout-inflateIfNeeded");
         inflateIfNeeded(params, wct, rootView, oldLayoutResId, outResult);
-        if (outResult.mRootView == null) {
-            // Didn't manage to create a root view, early out.
+        Trace.endSection();
+        final boolean hasCaptionView = outResult.mRootView != null;
+        if (!hasCaptionView) {
+            Trace.endSection(); // WindowDecoration#relayout
             return;
         }
-        rootView = null; // Clear it just in case we use it accidentally
 
+        Trace.beginSection("WindowDecoration#relayout-updateCaptionVisibility");
         updateCaptionVisibility(outResult.mRootView);
+        Trace.endSection();
 
         final Rect taskBounds = mTaskInfo.getConfiguration().windowConfiguration.getBounds();
         outResult.mWidth = taskBounds.width();
@@ -254,10 +255,23 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
                 ? loadDimensionPixelSize(resources, params.mCaptionWidthId) : taskBounds.width();
         outResult.mCaptionX = (outResult.mWidth - outResult.mCaptionWidth) / 2;
 
+        Trace.beginSection("WindowDecoration#relayout-acquire");
+        if (mDecorViewHost == null) {
+            mDecorViewHost = mWindowDecorViewHostSupplier.acquire(mDecorWindowContext, mDisplay);
+        }
+        Trace.endSection();
+
+        final SurfaceControl captionSurface = mDecorViewHost.getSurfaceControl();
+        Trace.beginSection("WindowDecoration#relayout-updateSurfacesAndInsets");
         updateDecorationContainerSurface(startT, outResult);
-        updateCaptionContainerSurface(startT, outResult);
+        updateCaptionContainerSurface(captionSurface, startT, outResult);
         updateCaptionInsets(params, wct, outResult, taskBounds);
         updateTaskSurface(params, startT, finishT, outResult);
+        Trace.endSection();
+
+        outResult.mRootView.setPadding(0, params.mCaptionTopPadding, 0, 0);
+        updateViewHierarchy(params, outResult, startT);
+        Trace.endSection(); // WindowDecoration#relayout
     }
 
     private void inflateIfNeeded(RelayoutParams params, WindowContainerTransaction wct,
@@ -305,6 +319,32 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
         return (T) LayoutInflater.from(context).inflate(layoutResId, null);
     }
 
+    private void updateViewHierarchy(@NonNull RelayoutParams params,
+            @NonNull RelayoutResult<T> outResult, @NonNull SurfaceControl.Transaction startT) {
+        Trace.beginSection("WindowDecoration#updateViewHierarchy");
+        final WindowManager.LayoutParams lp =
+                new WindowManager.LayoutParams(
+                        outResult.mCaptionWidth,
+                        outResult.mCaptionHeight,
+                        TYPE_APPLICATION,
+                        FLAG_NOT_FOCUSABLE | FLAG_SPLIT_TOUCH,
+                        PixelFormat.TRANSPARENT);
+        lp.setTitle("Caption of Task=" + mTaskInfo.taskId);
+        lp.setTrustedOverlay();
+        lp.inputFeatures = params.mInputFeatures;
+        if (params.mAsyncViewHost) {
+            if (params.mApplyStartTransactionOnDraw) {
+                throw new IllegalArgumentException(
+                        "We cannot both sync viewhost ondraw and delay viewhost creation.");
+            }
+            mDecorViewHost.updateViewAsync(outResult.mRootView, lp, mTaskInfo.getConfiguration());
+        } else {
+            mDecorViewHost.updateView(outResult.mRootView, lp, mTaskInfo.getConfiguration(),
+                    params.mApplyStartTransactionOnDraw ? startT : null);
+        }
+        Trace.endSection();
+    }
+
     private void updateDecorationContainerSurface(
             SurfaceControl.Transaction startT, RelayoutResult<T> outResult) {
         if (mDecorationContainerSurface == null) {
@@ -325,23 +365,14 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
                 .show(mDecorationContainerSurface);
     }
 
-    private void updateCaptionContainerSurface(
+    private void updateCaptionContainerSurface(@NonNull SurfaceControl captionSurface,
             SurfaceControl.Transaction startT, RelayoutResult<T> outResult) {
-        if (mCaptionContainerSurface == null) {
-            final SurfaceControl.Builder builder = mSurfaceControlBuilderSupplier.get();
-            mCaptionContainerSurface = builder
-                    .setName("Caption container of Task=" + mTaskInfo.taskId)
-                    .setContainerLayer()
-                    .setParent(mDecorationContainerSurface)
-                    .setCallsite("WindowDecoration.updateCaptionContainerSurface")
-                    .build();
-        }
-
-        startT.setWindowCrop(mCaptionContainerSurface, outResult.mCaptionWidth,
+        startT.reparent(captionSurface, mDecorationContainerSurface)
+                .setWindowCrop(captionSurface, outResult.mCaptionWidth,
                         outResult.mCaptionHeight)
-                .setPosition(mCaptionContainerSurface, outResult.mCaptionX, 0 /* y */)
-                .setLayer(mCaptionContainerSurface, CAPTION_LAYER_Z_ORDER)
-                .show(mCaptionContainerSurface);
+                .setPosition(captionSurface, outResult.mCaptionX, 0 /* y */)
+                .setLayer(captionSurface, CAPTION_LAYER_Z_ORDER)
+                .show(captionSurface);
     }
 
     private void updateCaptionInsets(RelayoutParams params, WindowContainerTransaction wct,
@@ -435,64 +466,6 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
         }
     }
 
-    /**
-     * Updates a {@link SurfaceControlViewHost} to connect the window decoration surfaces with our
-     * View hierarchy.
-     *
-     * @param params parameters to use from the last relayout
-     * @param onDrawTransaction a transaction to apply in sync with #onDraw
-     * @param outResult results to use from the last relayout
-     *
-     */
-    protected void updateViewHost(RelayoutParams params,
-            SurfaceControl.Transaction onDrawTransaction, RelayoutResult<T> outResult) {
-        Trace.beginSection("CaptionViewHostLayout");
-        if (mCaptionWindowManager == null) {
-            // Put caption under a container surface because ViewRootImpl sets the destination frame
-            // of windowless window layers and BLASTBufferQueue#update() doesn't support offset.
-            mCaptionWindowManager = new WindowlessWindowManager(
-                    mTaskInfo.getConfiguration(), mCaptionContainerSurface,
-                    null /* hostInputToken */);
-        }
-        mCaptionWindowManager.setConfiguration(mTaskInfo.getConfiguration());
-        final WindowManager.LayoutParams lp =
-                new WindowManager.LayoutParams(
-                        outResult.mCaptionWidth,
-                        outResult.mCaptionHeight,
-                        TYPE_APPLICATION,
-                        FLAG_NOT_FOCUSABLE | FLAG_SPLIT_TOUCH,
-                        PixelFormat.TRANSPARENT);
-        lp.setTitle("Caption of Task=" + mTaskInfo.taskId);
-        lp.setTrustedOverlay();
-        lp.inputFeatures = params.mInputFeatures;
-        if (mViewHost == null) {
-            Trace.beginSection("CaptionViewHostLayout-new");
-            mViewHost = mSurfaceControlViewHostFactory.create(mDecorWindowContext, mDisplay,
-                    mCaptionWindowManager);
-            if (params.mApplyStartTransactionOnDraw) {
-                if (onDrawTransaction == null) {
-                    throw new IllegalArgumentException("Trying to sync a null Transaction");
-                }
-                mViewHost.getRootSurfaceControl().applyTransactionOnDraw(onDrawTransaction);
-            }
-            outResult.mRootView.setPadding(0, params.mCaptionTopPadding, 0, 0);
-            mViewHost.setView(outResult.mRootView, lp);
-            Trace.endSection();
-        } else {
-            Trace.beginSection("CaptionViewHostLayout-relayout");
-            if (params.mApplyStartTransactionOnDraw) {
-                if (onDrawTransaction == null) {
-                    throw new IllegalArgumentException("Trying to sync a null Transaction");
-                }
-                mViewHost.getRootSurfaceControl().applyTransactionOnDraw(onDrawTransaction);
-            }
-            outResult.mRootView.setPadding(0, params.mCaptionTopPadding, 0, 0);
-            mViewHost.relayout(lp);
-            Trace.endSection();
-        }
-        Trace.endSection(); // CaptionViewHostLayout
-    }
-
     private Rect calculateBoundingRect(@NonNull OccludingCaptionElement element,
             int elementWidthPx, @NonNull Rect captionRect) {
         switch (element.mAlignment) {
@@ -580,18 +553,11 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
     }
 
     void releaseViews(WindowContainerTransaction wct) {
-        if (mViewHost != null) {
-            mViewHost.release();
-            mViewHost = null;
-        }
-
-        mCaptionWindowManager = null;
-
         final SurfaceControl.Transaction t = mSurfaceControlTransactionSupplier.get();
         boolean released = false;
-        if (mCaptionContainerSurface != null) {
-            t.remove(mCaptionContainerSurface);
-            mCaptionContainerSurface = null;
+        if (mDecorViewHost != null) {
+            mWindowDecorViewHostSupplier.release(mDecorViewHost, t);
+            mDecorViewHost = null;
             released = true;
         }
 
@@ -742,6 +708,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
 
         boolean mApplyStartTransactionOnDraw;
         boolean mSetTaskPositionAndCrop;
+        boolean mAsyncViewHost;
 
         void reset() {
             mLayoutResId = Resources.ID_NULL;
@@ -758,6 +725,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
 
             mApplyStartTransactionOnDraw = false;
             mSetTaskPositionAndCrop = false;
+            mAsyncViewHost = false;
             mWindowDecorConfig = null;
         }
 
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHost.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHost.kt
new file mode 100644
index 000000000000..139e6790b744
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHost.kt
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.wm.shell.windowdecor.viewhost
+
+import android.content.Context
+import android.content.res.Configuration
+import android.view.Display
+import android.view.SurfaceControl
+import android.view.SurfaceControlViewHost
+import android.view.View
+import android.view.WindowManager
+import android.view.WindowlessWindowManager
+import androidx.tracing.Trace
+import com.android.internal.annotations.VisibleForTesting
+import com.android.wm.shell.shared.annotations.ShellMainThread
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+typealias SurfaceControlViewHostFactory =
+            (Context, Display, WindowlessWindowManager, String) -> SurfaceControlViewHost
+
+/**
+ * A default implementation of [WindowDecorViewHost] backed by a [SurfaceControlViewHost].
+ *
+ * It does not support swapping the root view added to the VRI of the [SurfaceControlViewHost], and
+ * any attempts to do will throw, which means that once a [View] is added using [updateView] or
+ * [updateViewAsync], only its properties and binding may be changed, its children views may be
+ * added, removed or changed and its [WindowManager.LayoutParams] may be changed.
+ * It also supports asynchronously updating the view hierarchy using [updateViewAsync], in which
+ * case the update work will be posted on the [ShellMainThread] with no delay.
+ */
+class DefaultWindowDecorViewHost(
+    private val context: Context,
+    @ShellMainThread private val mainScope: CoroutineScope,
+    private val display: Display,
+    private val surfaceControlViewHostFactory: SurfaceControlViewHostFactory = { c, d, wwm, s ->
+        SurfaceControlViewHost(c, d, wwm, s)
+    }
+) : WindowDecorViewHost {
+
+    private val rootSurface: SurfaceControl = SurfaceControl.Builder()
+            .setName("DefaultWindowDecorViewHost surface")
+            .setContainerLayer()
+            .setCallsite("DefaultWindowDecorViewHost#init")
+            .build()
+
+    private var wwm: WindowlessWindowManager? = null
+    @VisibleForTesting
+    var viewHost: SurfaceControlViewHost? = null
+    private var currentUpdateJob: Job? = null
+
+    override val surfaceControl: SurfaceControl
+        get() = rootSurface
+
+    override fun updateView(
+        view: View,
+        attrs: WindowManager.LayoutParams,
+        configuration: Configuration,
+        onDrawTransaction: SurfaceControl.Transaction?
+    ) {
+        Trace.beginSection("DefaultWindowDecorViewHost#updateView")
+        clearCurrentUpdateJob()
+        updateViewHost(view, attrs, configuration, onDrawTransaction)
+        Trace.endSection()
+    }
+
+    override fun updateViewAsync(
+        view: View,
+        attrs: WindowManager.LayoutParams,
+        configuration: Configuration
+    ) {
+        Trace.beginSection("DefaultWindowDecorViewHost#updateViewAsync")
+        clearCurrentUpdateJob()
+        currentUpdateJob = mainScope.launch {
+            updateViewHost(view, attrs, configuration, onDrawTransaction = null)
+        }
+        Trace.endSection()
+    }
+
+    override fun release(t: SurfaceControl.Transaction) {
+        clearCurrentUpdateJob()
+        viewHost?.release()
+        t.remove(rootSurface)
+    }
+
+    private fun updateViewHost(
+        view: View,
+        attrs: WindowManager.LayoutParams,
+        configuration: Configuration,
+        onDrawTransaction: SurfaceControl.Transaction?
+    ) {
+        Trace.beginSection("DefaultWindowDecorViewHost#updateViewHost")
+        if (wwm == null) {
+            wwm = WindowlessWindowManager(configuration, rootSurface, null)
+        }
+        requireWindowlessWindowManager().setConfiguration(configuration)
+        if (viewHost == null) {
+            viewHost = surfaceControlViewHostFactory.invoke(
+                context,
+                display,
+                requireWindowlessWindowManager(),
+                "DefaultWindowDecorViewHost#updateViewHost"
+            )
+        }
+        onDrawTransaction?.let {
+            requireViewHost().rootSurfaceControl.applyTransactionOnDraw(it)
+        }
+        if (requireViewHost().view == null) {
+            Trace.beginSection("DefaultWindowDecorViewHost#updateViewHost-setView")
+            requireViewHost().setView(view, attrs)
+            Trace.endSection()
+        } else {
+            check(requireViewHost().view == view) { "Changing view is not allowed" }
+            Trace.beginSection("DefaultWindowDecorViewHost#updateViewHost-relayout")
+            requireViewHost().relayout(attrs)
+            Trace.endSection()
+        }
+        Trace.endSection()
+    }
+
+    private fun clearCurrentUpdateJob() {
+        currentUpdateJob?.cancel()
+        currentUpdateJob = null
+    }
+
+    private fun requireWindowlessWindowManager(): WindowlessWindowManager {
+        return wwm ?: error("Expected non-null windowless window manager")
+    }
+
+    private fun requireViewHost(): SurfaceControlViewHost {
+        return viewHost ?: error("Expected non-null view host")
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHostSupplier.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHostSupplier.kt
new file mode 100644
index 000000000000..9997e8f564d8
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHostSupplier.kt
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.wm.shell.windowdecor.viewhost
+
+import android.content.Context
+import android.view.Display
+import android.view.SurfaceControl
+import com.android.wm.shell.shared.annotations.ShellMainThread
+import kotlinx.coroutines.CoroutineScope
+
+/**
+ * A supplier of [DefaultWindowDecorViewHost]s. It creates a new one every time one is requested.
+ */
+class DefaultWindowDecorViewHostSupplier(
+    @ShellMainThread private val mainScope: CoroutineScope,
+) : WindowDecorViewHostSupplier<DefaultWindowDecorViewHost> {
+
+    override fun acquire(context: Context, display: Display): DefaultWindowDecorViewHost {
+        return DefaultWindowDecorViewHost(context, mainScope, display)
+    }
+
+    override fun release(viewHost: DefaultWindowDecorViewHost, t: SurfaceControl.Transaction) {
+        viewHost.release(t)
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/WindowDecorViewHost.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/WindowDecorViewHost.kt
new file mode 100644
index 000000000000..3fbaea8bd1bf
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/WindowDecorViewHost.kt
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.wm.shell.windowdecor.viewhost
+
+import android.content.res.Configuration
+import android.view.SurfaceControl
+import android.view.View
+import android.view.WindowManager
+import com.android.wm.shell.windowdecor.WindowDecoration
+
+/**
+ * An interface for a utility that hosts a [WindowDecoration]'s [View] hierarchy under a
+ * [SurfaceControl].
+ */
+interface WindowDecorViewHost {
+    /** The surface where the underlying [View] hierarchy is being rendered. */
+    val surfaceControl: SurfaceControl
+
+    /** Synchronously update the view hierarchy of this view host. */
+    fun updateView(
+        view: View,
+        attrs: WindowManager.LayoutParams,
+        configuration: Configuration,
+        onDrawTransaction: SurfaceControl.Transaction?
+    )
+
+    /** Asynchronously update the view hierarchy of this view host. */
+    fun updateViewAsync(
+        view: View,
+        attrs: WindowManager.LayoutParams,
+        configuration: Configuration
+    )
+
+    /** Releases the underlying [View] hierarchy and removes the backing [SurfaceControl]. */
+    fun release(t: SurfaceControl.Transaction)
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/WindowDecorViewHostSupplier.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/WindowDecorViewHostSupplier.kt
new file mode 100644
index 000000000000..0e2358446d12
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewhost/WindowDecorViewHostSupplier.kt
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.wm.shell.windowdecor.viewhost
+
+import android.content.Context
+import android.view.Display
+import android.view.SurfaceControl
+
+/**
+ * An interface for a supplier of [WindowDecorViewHost]s.
+ */
+interface WindowDecorViewHostSupplier<T : WindowDecorViewHost> {
+    /** Acquire a [WindowDecorViewHost]. */
+    fun acquire(context: Context, display: Display): T
+
+    /**
+     * Release a [WindowDecorViewHost] when it is no longer used.
+     *
+     * @param viewHost the [WindowDecorViewHost] to release
+     * @param t a transaction that may be used to remove any underlying backing [SurfaceControl]
+     *          that are hosting this [WindowDecorViewHost]. The supplier is not expected to apply
+     *          the transaction. It should be applied by the owner of this supplier.
+     */
+    fun release(viewHost: T, t: SurfaceControl.Transaction)
+}
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModelTests.kt b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModelTests.kt
index 2c805e8e77b3..a17d08d8fbfb 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModelTests.kt
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModelTests.kt
@@ -98,6 +98,7 @@ import com.android.wm.shell.sysui.ShellInit
 import com.android.wm.shell.transition.Transitions
 import com.android.wm.shell.windowdecor.DesktopModeWindowDecorViewModel.DesktopModeKeyguardChangeListener
 import com.android.wm.shell.windowdecor.DesktopModeWindowDecorViewModel.DesktopModeOnInsetsChangedListener
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier
 import java.util.Optional
 import java.util.function.Consumer
 import java.util.function.Supplier
@@ -181,6 +182,7 @@ class DesktopModeWindowDecorViewModelTests : ShellTestCase() {
     @Mock private lateinit var mockTaskPositionerFactory:
             DesktopModeWindowDecorViewModel.TaskPositionerFactory
     @Mock private lateinit var mockTaskPositioner: TaskPositioner
+    @Mock private lateinit var mockWindowDecorViewHostSupplier: WindowDecorViewHostSupplier<*>
     private lateinit var spyContext: TestableContext
 
     private val transactionFactory = Supplier<SurfaceControl.Transaction> {
@@ -230,6 +232,7 @@ class DesktopModeWindowDecorViewModelTests : ShellTestCase() {
                 mockGenericLinksParser,
                 mockAssistContentRequester,
                 mockMultiInstanceHelper,
+                mockWindowDecorViewHostSupplier,
                 mockDesktopModeWindowDecorFactory,
                 mockInputMonitorFactory,
                 transactionFactory,
@@ -1197,7 +1200,7 @@ class DesktopModeWindowDecorViewModelTests : ShellTestCase() {
         whenever(
             mockDesktopModeWindowDecorFactory.create(
                 any(), any(), any(), any(), any(), eq(task), any(), any(), any(), any(), any(),
-                any(), any(), any(), any())
+                any(), any(), any(), any(), any())
         ).thenReturn(decoration)
         decoration.mTaskInfo = task
         whenever(decoration.isFocused).thenReturn(task.isFocused)
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorationTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorationTests.java
index b9e542a0e0c1..7b68ddf64fce 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorationTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorationTests.java
@@ -97,6 +97,8 @@ import com.android.wm.shell.common.SyncTransactionQueue;
 import com.android.wm.shell.shared.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.splitscreen.SplitScreenController;
 import com.android.wm.shell.windowdecor.WindowDecoration.RelayoutParams;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHost;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 import kotlin.Unit;
 import kotlin.jvm.functions.Function0;
@@ -162,6 +164,10 @@ public class DesktopModeWindowDecorationTests extends ShellTestCase {
     @Mock
     private WindowDecoration.SurfaceControlViewHostFactory mMockSurfaceControlViewHostFactory;
     @Mock
+    private WindowDecorViewHostSupplier mMockWindowDecorViewHostSupplier;
+    @Mock
+    private WindowDecorViewHost mMockWindowDecorViewHost;
+    @Mock
     private TypedArray mMockRoundedCornersRadiusArray;
     @Mock
     private TestTouchEventListener mMockTouchEventListener;
@@ -233,6 +239,9 @@ public class DesktopModeWindowDecorationTests extends ShellTestCase {
                 any(), anyBoolean(), anyBoolean(), any(), anyInt(), anyInt(), anyInt()))
                 .thenReturn(mMockHandleMenu);
         when(mMockMultiInstanceHelper.supportsMultiInstanceSplit(any())).thenReturn(false);
+        when(mMockWindowDecorViewHostSupplier.acquire(any(), eq(defaultDisplay)))
+                .thenReturn(mMockWindowDecorViewHost);
+        when(mMockWindowDecorViewHost.getSurfaceControl()).thenReturn(mock(SurfaceControl.class));
     }
 
     @After
@@ -504,58 +513,55 @@ public class DesktopModeWindowDecorationTests extends ShellTestCase {
     }
 
     @Test
-    public void relayout_fullscreenTask_appliesTransactionImmediately() {
+    public void updateRelayoutParams_handle_requestsAsyncViewHostRendering() {
         final ActivityManager.RunningTaskInfo taskInfo = createTaskInfo(/* visible= */ true);
-        final DesktopModeWindowDecoration spyWindowDecor = spy(createWindowDecoration(taskInfo));
+        // Make the task fullscreen so that its decoration is an App Handle.
         taskInfo.configuration.windowConfiguration.setWindowingMode(WINDOWING_MODE_FULLSCREEN);
+        final RelayoutParams relayoutParams = new RelayoutParams();
 
-        spyWindowDecor.relayout(taskInfo);
+        DesktopModeWindowDecoration.updateRelayoutParams(
+                relayoutParams,
+                mTestableContext,
+                taskInfo,
+                /* applyStartTransactionOnDraw= */ true,
+                /* shouldSetTaskPositionAndCrop */ false);
 
-        verify(mMockTransaction).apply();
-        verify(mMockRootSurfaceControl, never()).applyTransactionOnDraw(any());
+        // App Handles don't need to be rendered in sync with the task animation, per UX.
+        assertThat(relayoutParams.mAsyncViewHost).isTrue();
     }
 
     @Test
-    public void relayout_freeformTask_appliesTransactionOnDraw() {
+    public void updateRelayoutParams_header_requestsSyncViewHostRendering() {
         final ActivityManager.RunningTaskInfo taskInfo = createTaskInfo(/* visible= */ true);
-        final DesktopModeWindowDecoration spyWindowDecor = spy(createWindowDecoration(taskInfo));
+        // Make the task freeform so that its decoration is an App Header.
         taskInfo.configuration.windowConfiguration.setWindowingMode(WINDOWING_MODE_FREEFORM);
-        // Make non-resizable to avoid dealing with input-permissions (MONITOR_INPUT)
-        taskInfo.isResizeable = false;
-
-        spyWindowDecor.relayout(taskInfo);
-
-        verify(mMockTransaction, never()).apply();
-        verify(mMockRootSurfaceControl).applyTransactionOnDraw(mMockTransaction);
-    }
-
-    @Test
-    public void relayout_fullscreenTask_doesNotCreateViewHostImmediately() {
-        final ActivityManager.RunningTaskInfo taskInfo = createTaskInfo(/* visible= */ true);
-        final DesktopModeWindowDecoration spyWindowDecor = spy(createWindowDecoration(taskInfo));
-        taskInfo.configuration.windowConfiguration.setWindowingMode(WINDOWING_MODE_FULLSCREEN);
+        final RelayoutParams relayoutParams = new RelayoutParams();
 
-        spyWindowDecor.relayout(taskInfo);
+        DesktopModeWindowDecoration.updateRelayoutParams(
+                relayoutParams,
+                mTestableContext,
+                taskInfo,
+                /* applyStartTransactionOnDraw= */ true,
+                /* shouldSetTaskPositionAndCrop */ false);
 
-        verify(mMockSurfaceControlViewHostFactory, never()).create(any(), any(), any());
+        // App Headers must be rendered in sync with the task animation, so it cannot be delayed.
+        assertThat(relayoutParams.mAsyncViewHost).isFalse();
     }
 
     @Test
-    public void relayout_fullscreenTask_postsViewHostCreation() {
+    public void relayout_fullscreenTask_appliesTransactionImmediately() {
         final ActivityManager.RunningTaskInfo taskInfo = createTaskInfo(/* visible= */ true);
         final DesktopModeWindowDecoration spyWindowDecor = spy(createWindowDecoration(taskInfo));
         taskInfo.configuration.windowConfiguration.setWindowingMode(WINDOWING_MODE_FULLSCREEN);
 
-        ArgumentCaptor<Runnable> runnableArgument = ArgumentCaptor.forClass(Runnable.class);
         spyWindowDecor.relayout(taskInfo);
 
-        verify(mMockHandler).post(runnableArgument.capture());
-        runnableArgument.getValue().run();
-        verify(mMockSurfaceControlViewHostFactory).create(any(), any(), any());
+        verify(mMockTransaction).apply();
+        verify(mMockRootSurfaceControl, never()).applyTransactionOnDraw(any());
     }
 
     @Test
-    public void relayout_freeformTask_createsViewHostImmediately() {
+    public void relayout_freeformTask_appliesTransactionOnDraw() {
         final ActivityManager.RunningTaskInfo taskInfo = createTaskInfo(/* visible= */ true);
         final DesktopModeWindowDecoration spyWindowDecor = spy(createWindowDecoration(taskInfo));
         taskInfo.configuration.windowConfiguration.setWindowingMode(WINDOWING_MODE_FREEFORM);
@@ -564,36 +570,8 @@ public class DesktopModeWindowDecorationTests extends ShellTestCase {
 
         spyWindowDecor.relayout(taskInfo);
 
-        verify(mMockSurfaceControlViewHostFactory).create(any(), any(), any());
-        verify(mMockHandler, never()).post(any());
-    }
-
-    @Test
-    public void relayout_removesExistingHandlerCallback() {
-        final ActivityManager.RunningTaskInfo taskInfo = createTaskInfo(/* visible= */ true);
-        final DesktopModeWindowDecoration spyWindowDecor = spy(createWindowDecoration(taskInfo));
-        taskInfo.configuration.windowConfiguration.setWindowingMode(WINDOWING_MODE_FULLSCREEN);
-        ArgumentCaptor<Runnable> runnableArgument = ArgumentCaptor.forClass(Runnable.class);
-        spyWindowDecor.relayout(taskInfo);
-        verify(mMockHandler).post(runnableArgument.capture());
-
-        spyWindowDecor.relayout(taskInfo);
-
-        verify(mMockHandler).removeCallbacks(runnableArgument.getValue());
-    }
-
-    @Test
-    public void close_removesExistingHandlerCallback() {
-        final ActivityManager.RunningTaskInfo taskInfo = createTaskInfo(/* visible= */ true);
-        final DesktopModeWindowDecoration spyWindowDecor = spy(createWindowDecoration(taskInfo));
-        taskInfo.configuration.windowConfiguration.setWindowingMode(WINDOWING_MODE_FULLSCREEN);
-        ArgumentCaptor<Runnable> runnableArgument = ArgumentCaptor.forClass(Runnable.class);
-        spyWindowDecor.relayout(taskInfo);
-        verify(mMockHandler).post(runnableArgument.capture());
-
-        spyWindowDecor.close();
-
-        verify(mMockHandler).removeCallbacks(runnableArgument.getValue());
+        verify(mMockTransaction, never()).apply();
+        verify(mMockWindowDecorViewHost).updateView(any(), any(), any(), eq(mMockTransaction));
     }
 
     @Test
@@ -924,7 +902,8 @@ public class DesktopModeWindowDecorationTests extends ShellTestCase {
                 mMockGenericLinksParser, mMockAssistContentRequester, SurfaceControl.Builder::new,
                 mMockTransactionSupplier, WindowContainerTransaction::new, SurfaceControl::new,
                 new WindowManagerWrapper(mMockWindowManager), mMockSurfaceControlViewHostFactory,
-                maximizeMenuFactory, mMockHandleMenuFactory, mMockMultiInstanceHelper);
+                mMockWindowDecorViewHostSupplier, maximizeMenuFactory, mMockHandleMenuFactory,
+                mMockMultiInstanceHelper);
         windowDecor.setCaptionListeners(mMockTouchEventListener, mMockTouchEventListener,
                 mMockTouchEventListener, mMockTouchEventListener);
         windowDecor.setExclusionRegionListener(mMockExclusionRegionListener);
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/WindowDecorationTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/WindowDecorationTests.java
index 2e117ac9f865..7252b32efc6b 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/WindowDecorationTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/WindowDecorationTests.java
@@ -85,6 +85,8 @@ import com.android.wm.shell.common.DisplayController;
 import com.android.wm.shell.shared.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.tests.R;
 import com.android.wm.shell.windowdecor.additionalviewcontainer.AdditionalViewContainer;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHost;
+import com.android.wm.shell.windowdecor.viewhost.WindowDecorViewHostSupplier;
 
 import org.junit.Before;
 import org.junit.Rule;
@@ -128,6 +130,10 @@ public class WindowDecorationTests extends ShellTestCase {
     @Mock
     private SurfaceControlViewHost mMockSurfaceControlViewHost;
     @Mock
+    private WindowDecorViewHostSupplier mMockWindowDecorViewHostSupplier;
+    @Mock
+    private WindowDecorViewHost mMockWindowDecorViewHost;
+    @Mock
     private AttachedSurfaceControl mMockRootSurfaceControl;
     @Mock
     private TestView mMockView;
@@ -167,6 +173,9 @@ public class WindowDecorationTests extends ShellTestCase {
         when(mMockSurfaceControlViewHost.getRootSurfaceControl())
                 .thenReturn(mMockRootSurfaceControl);
         when(mMockView.findViewById(anyInt())).thenReturn(mMockView);
+        when(mMockWindowDecorViewHostSupplier.acquire(any(), any()))
+                .thenReturn(mMockWindowDecorViewHost);
+        when(mMockWindowDecorViewHost.getSurfaceControl()).thenReturn(mock(SurfaceControl.class));
 
         // Add status bar inset so that WindowDecoration does not think task is in immersive mode
         mInsetsState.getOrCreateSource(STATUS_BAR_INSET_SOURCE_ID, statusBars()).setVisible(true);
@@ -230,10 +239,6 @@ public class WindowDecorationTests extends ShellTestCase {
         final SurfaceControl.Builder decorContainerSurfaceBuilder =
                 createMockSurfaceControlBuilder(decorContainerSurface);
         mMockSurfaceControlBuilders.add(decorContainerSurfaceBuilder);
-        final SurfaceControl captionContainerSurface = mock(SurfaceControl.class);
-        final SurfaceControl.Builder captionContainerSurfaceBuilder =
-                createMockSurfaceControlBuilder(captionContainerSurface);
-        mMockSurfaceControlBuilders.add(captionContainerSurfaceBuilder);
 
         final ActivityManager.RunningTaskInfo taskInfo = new TestRunningTaskInfoBuilder()
                 .setDisplayId(Display.DEFAULT_DISPLAY)
@@ -254,18 +259,18 @@ public class WindowDecorationTests extends ShellTestCase {
         verify(mMockSurfaceControlStartT).setTrustedOverlay(decorContainerSurface, true);
         verify(mMockSurfaceControlStartT).setWindowCrop(decorContainerSurface, 300, 100);
 
-        verify(captionContainerSurfaceBuilder).setParent(decorContainerSurface);
-        verify(captionContainerSurfaceBuilder).setContainerLayer();
+        final SurfaceControl captionContainerSurface = mMockWindowDecorViewHost.getSurfaceControl();
+        verify(mMockSurfaceControlStartT).reparent(captionContainerSurface, decorContainerSurface);
         verify(mMockSurfaceControlStartT).setWindowCrop(captionContainerSurface, 300, 64);
         verify(mMockSurfaceControlStartT).show(captionContainerSurface);
 
-        verify(mMockSurfaceControlViewHostFactory).create(any(), eq(defaultDisplay), any());
-
-        verify(mMockSurfaceControlViewHost)
-                .setView(same(mMockView),
-                        argThat(lp -> lp.height == 64
-                                && lp.width == 300
-                                && (lp.flags & LayoutParams.FLAG_NOT_FOCUSABLE) != 0));
+        verify(mMockWindowDecorViewHost).updateView(
+                same(mMockView),
+                argThat(lp -> lp.height == 64
+                        && lp.width == 300
+                        && (lp.flags & LayoutParams.FLAG_NOT_FOCUSABLE) != 0),
+                eq(taskInfo.configuration),
+                eq(null) /* onDrawTransaction */);
         verify(mMockView).setTaskFocusState(true);
         verify(mMockWindowContainerTransaction).addInsetsSource(
                 eq(taskInfo.token),
@@ -296,10 +301,6 @@ public class WindowDecorationTests extends ShellTestCase {
         final SurfaceControl.Builder decorContainerSurfaceBuilder =
                 createMockSurfaceControlBuilder(decorContainerSurface);
         mMockSurfaceControlBuilders.add(decorContainerSurfaceBuilder);
-        final SurfaceControl captionContainerSurface = mock(SurfaceControl.class);
-        final SurfaceControl.Builder captionContainerSurfaceBuilder =
-                createMockSurfaceControlBuilder(captionContainerSurface);
-        mMockSurfaceControlBuilders.add(captionContainerSurfaceBuilder);
 
         final SurfaceControl.Transaction t = mock(SurfaceControl.Transaction.class);
         mMockSurfaceControlTransactions.add(t);
@@ -322,7 +323,7 @@ public class WindowDecorationTests extends ShellTestCase {
 
         windowDecor.relayout(taskInfo);
 
-        verify(mMockSurfaceControlViewHost, never()).release();
+        verify(mMockWindowDecorViewHost, never()).release(any());
         verify(t, never()).apply();
         verify(mMockWindowContainerTransaction, never())
                 .removeInsetsSource(eq(taskInfo.token), any(), anyInt(), anyInt());
@@ -332,9 +333,8 @@ public class WindowDecorationTests extends ShellTestCase {
         taskInfo.isVisible = false;
         windowDecor.relayout(taskInfo);
 
-        final InOrder releaseOrder = inOrder(t2, mMockSurfaceControlViewHost);
-        releaseOrder.verify(mMockSurfaceControlViewHost).release();
-        releaseOrder.verify(t2).remove(captionContainerSurface);
+        final InOrder releaseOrder = inOrder(t2, mMockWindowDecorViewHostSupplier);
+        releaseOrder.verify(mMockWindowDecorViewHostSupplier).release(mMockWindowDecorViewHost, t2);
         releaseOrder.verify(t2).remove(decorContainerSurface);
         releaseOrder.verify(t2).apply();
         // Expect to remove two insets sources, the caption insets and the mandatory gesture insets.
@@ -382,8 +382,8 @@ public class WindowDecorationTests extends ShellTestCase {
         verify(mMockDisplayController).removeDisplayWindowListener(same(listener));
 
         assertThat(mRelayoutResult.mRootView).isSameInstanceAs(mMockView);
-        verify(mMockSurfaceControlViewHostFactory).create(any(), eq(mockDisplay), any());
-        verify(mMockSurfaceControlViewHost).setView(same(mMockView), any());
+        verify(mMockWindowDecorViewHostSupplier).acquire(any(), eq(mockDisplay));
+        verify(mMockWindowDecorViewHost).updateView(same(mMockView), any(), any(), any());
     }
 
     @Test
@@ -396,10 +396,6 @@ public class WindowDecorationTests extends ShellTestCase {
         final SurfaceControl.Builder decorContainerSurfaceBuilder =
                 createMockSurfaceControlBuilder(decorContainerSurface);
         mMockSurfaceControlBuilders.add(decorContainerSurfaceBuilder);
-        final SurfaceControl captionContainerSurface = mock(SurfaceControl.class);
-        final SurfaceControl.Builder captionContainerSurfaceBuilder =
-                createMockSurfaceControlBuilder(captionContainerSurface);
-        mMockSurfaceControlBuilders.add(captionContainerSurfaceBuilder);
 
         final SurfaceControl.Transaction t = mock(SurfaceControl.Transaction.class);
         mMockSurfaceControlTransactions.add(t);
@@ -436,8 +432,7 @@ public class WindowDecorationTests extends ShellTestCase {
                 windowDecor.mDecorWindowContext.getResources(), mRelayoutParams.mCaptionHeightId);
         verify(mMockSurfaceControlAddWindowT).setWindowCrop(additionalWindowSurface, width, height);
         verify(mMockSurfaceControlAddWindowT).show(additionalWindowSurface);
-        verify(mMockSurfaceControlViewHostFactory, Mockito.times(2))
-                .create(any(), eq(defaultDisplay), any());
+        verify(mMockSurfaceControlViewHostFactory).create(any(), eq(defaultDisplay), any());
     }
 
     @Test
@@ -450,10 +445,6 @@ public class WindowDecorationTests extends ShellTestCase {
         final SurfaceControl.Builder decorContainerSurfaceBuilder =
                 createMockSurfaceControlBuilder(decorContainerSurface);
         mMockSurfaceControlBuilders.add(decorContainerSurfaceBuilder);
-        final SurfaceControl captionContainerSurface = mock(SurfaceControl.class);
-        final SurfaceControl.Builder captionContainerSurfaceBuilder =
-                createMockSurfaceControlBuilder(captionContainerSurface);
-        mMockSurfaceControlBuilders.add(captionContainerSurfaceBuilder);
 
         final SurfaceControl.Transaction t = mock(SurfaceControl.Transaction.class);
         mMockSurfaceControlTransactions.add(t);
@@ -473,8 +464,8 @@ public class WindowDecorationTests extends ShellTestCase {
 
         windowDecor.relayout(taskInfo);
 
-        verify(captionContainerSurfaceBuilder).setParent(decorContainerSurface);
-        verify(captionContainerSurfaceBuilder).setContainerLayer();
+        final SurfaceControl captionContainerSurface = mMockWindowDecorViewHost.getSurfaceControl();
+        verify(mMockSurfaceControlStartT).reparent(captionContainerSurface, decorContainerSurface);
         // Width of the captionContainerSurface should match the width of TASK_BOUNDS
         verify(mMockSurfaceControlStartT).setWindowCrop(captionContainerSurface, 300, 64);
         verify(mMockSurfaceControlStartT).show(captionContainerSurface);
@@ -490,10 +481,6 @@ public class WindowDecorationTests extends ShellTestCase {
         final SurfaceControl.Builder decorContainerSurfaceBuilder =
                 createMockSurfaceControlBuilder(decorContainerSurface);
         mMockSurfaceControlBuilders.add(decorContainerSurfaceBuilder);
-        final SurfaceControl captionContainerSurface = mock(SurfaceControl.class);
-        final SurfaceControl.Builder captionContainerSurfaceBuilder =
-                createMockSurfaceControlBuilder(captionContainerSurface);
-        mMockSurfaceControlBuilders.add(captionContainerSurfaceBuilder);
 
         final SurfaceControl.Transaction t = mock(SurfaceControl.Transaction.class);
         mMockSurfaceControlTransactions.add(t);
@@ -511,9 +498,11 @@ public class WindowDecorationTests extends ShellTestCase {
         taskInfo.configuration.densityDpi = DisplayMetrics.DENSITY_DEFAULT * 2;
         final TestWindowDecoration windowDecor = createWindowDecoration(taskInfo);
 
-        windowDecor.relayout(taskInfo, true /* applyStartTransactionOnDraw */);
+        mRelayoutParams.mApplyStartTransactionOnDraw = true;
+        windowDecor.relayout(taskInfo);
 
-        verify(mMockRootSurfaceControl).applyTransactionOnDraw(mMockSurfaceControlStartT);
+        verify(mMockWindowDecorViewHost).updateView(any(), any(), any(),
+                eq(mMockSurfaceControlStartT));
     }
 
     @Test
@@ -867,37 +856,52 @@ public class WindowDecorationTests extends ShellTestCase {
     }
 
     @Test
-    public void updateViewHost_applyTransactionOnDrawIsTrue_surfaceControlIsUpdated() {
+    public void relayout_applyTransactionOnDrawIsTrue_updatesViewWithDrawTransaction() {
         final TestWindowDecoration windowDecor = createWindowDecoration(
-                new TestRunningTaskInfoBuilder().build());
+                new TestRunningTaskInfoBuilder()
+                        .setVisible(true)
+                        .setWindowingMode(WINDOWING_MODE_FREEFORM)
+                        .build());
         mRelayoutParams.mApplyStartTransactionOnDraw = true;
         mRelayoutResult.mRootView = mMockView;
 
-        windowDecor.updateViewHost(mRelayoutParams, mMockSurfaceControlStartT, mRelayoutResult);
+        windowDecor.relayout(windowDecor.mTaskInfo);
 
-        verify(mMockRootSurfaceControl).applyTransactionOnDraw(mMockSurfaceControlStartT);
+        verify(mMockWindowDecorViewHost)
+                .updateView(eq(mRelayoutResult.mRootView), any(),
+                        eq(windowDecor.mTaskInfo.configuration), eq(mMockSurfaceControlStartT));
     }
 
     @Test
-    public void updateViewHost_nullDrawTransaction_applyTransactionOnDrawIsTrue_throwsException() {
+    public void relayout_applyTransactionOnDrawIsTrue_asyncViewHostRendering_throwsException() {
         final TestWindowDecoration windowDecor = createWindowDecoration(
-                new TestRunningTaskInfoBuilder().build());
+                new TestRunningTaskInfoBuilder()
+                        .setVisible(true)
+                        .setWindowingMode(WINDOWING_MODE_FULLSCREEN)
+                        .build());
         mRelayoutParams.mApplyStartTransactionOnDraw = true;
+        mRelayoutParams.mAsyncViewHost = true;
         mRelayoutResult.mRootView = mMockView;
 
         assertThrows(IllegalArgumentException.class,
-                () -> windowDecor.updateViewHost(
-                        mRelayoutParams, null /* onDrawTransaction */, mRelayoutResult));
+                () -> windowDecor.relayout(windowDecor.mTaskInfo));
     }
 
     @Test
-    public void updateViewHost_nullDrawTransaction_applyTransactionOnDrawIsFalse_doesNotThrow() {
+    public void relayout_asyncViewHostRendering() {
         final TestWindowDecoration windowDecor = createWindowDecoration(
-                new TestRunningTaskInfoBuilder().build());
-        mRelayoutParams.mApplyStartTransactionOnDraw = false;
+                new TestRunningTaskInfoBuilder()
+                        .setVisible(true)
+                        .setWindowingMode(WINDOWING_MODE_FULLSCREEN)
+                        .build());
+        mRelayoutParams.mAsyncViewHost = true;
         mRelayoutResult.mRootView = mMockView;
 
-        windowDecor.updateViewHost(mRelayoutParams, null /* onDrawTransaction */, mRelayoutResult);
+        windowDecor.relayout(windowDecor.mTaskInfo);
+
+        verify(mMockWindowDecorViewHost)
+                .updateViewAsync(eq(mRelayoutResult.mRootView), any(),
+                        eq(windowDecor.mTaskInfo.configuration));
     }
 
     @Test
@@ -997,7 +1001,8 @@ public class WindowDecorationTests extends ShellTestCase {
                 new MockObjectSupplier<>(mMockSurfaceControlTransactions,
                         () -> mock(SurfaceControl.Transaction.class)),
                 () -> mMockWindowContainerTransaction, () -> mMockTaskSurface,
-                mMockSurfaceControlViewHostFactory);
+                mMockSurfaceControlViewHostFactory,
+                mMockWindowDecorViewHostSupplier);
     }
 
     private class MockObjectSupplier<T> implements Supplier<T> {
@@ -1037,16 +1042,20 @@ public class WindowDecorationTests extends ShellTestCase {
                 Supplier<SurfaceControl.Transaction> surfaceControlTransactionSupplier,
                 Supplier<WindowContainerTransaction> windowContainerTransactionSupplier,
                 Supplier<SurfaceControl> surfaceControlSupplier,
-                SurfaceControlViewHostFactory surfaceControlViewHostFactory) {
+                SurfaceControlViewHostFactory surfaceControlViewHostFactory,
+                @NonNull WindowDecorViewHostSupplier windowDecorViewHostSupplier) {
             super(context, userContext, displayController, taskOrganizer, taskInfo, taskSurface,
                     surfaceControlBuilderSupplier, surfaceControlTransactionSupplier,
                     windowContainerTransactionSupplier, surfaceControlSupplier,
-                    surfaceControlViewHostFactory);
+                    surfaceControlViewHostFactory, windowDecorViewHostSupplier);
         }
 
         @Override
         void relayout(ActivityManager.RunningTaskInfo taskInfo) {
-            relayout(taskInfo, false /* applyStartTransactionOnDraw */);
+            mRelayoutParams.mRunningTaskInfo = taskInfo;
+            mRelayoutParams.mLayoutResId = R.layout.caption_layout;
+            relayout(mRelayoutParams, mMockSurfaceControlStartT, mMockSurfaceControlFinishT,
+                    mMockWindowContainerTransaction, mMockView, mRelayoutResult);
         }
 
         @Override
@@ -1067,15 +1076,6 @@ public class WindowDecorationTests extends ShellTestCase {
             return super.inflateLayout(context, layoutResId);
         }
 
-        void relayout(ActivityManager.RunningTaskInfo taskInfo,
-                boolean applyStartTransactionOnDraw) {
-            mRelayoutParams.mRunningTaskInfo = taskInfo;
-            mRelayoutParams.mApplyStartTransactionOnDraw = applyStartTransactionOnDraw;
-            mRelayoutParams.mLayoutResId = R.layout.caption_layout;
-            relayout(mRelayoutParams, mMockSurfaceControlStartT, mMockSurfaceControlFinishT,
-                    mMockWindowContainerTransaction, mMockView, mRelayoutResult);
-        }
-
         private AdditionalViewContainer addTestViewContainer() {
             final Resources resources = mDecorWindowContext.getResources();
             final int width = loadDimensionPixelSize(resources, mCaptionMenuWidthId);
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHostTest.kt b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHostTest.kt
new file mode 100644
index 000000000000..1b2ce9e4df36
--- /dev/null
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/viewhost/DefaultWindowDecorViewHostTest.kt
@@ -0,0 +1,222 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.wm.shell.windowdecor.viewhost
+
+import android.testing.AndroidTestingRunner
+import android.testing.TestableLooper
+import android.view.SurfaceControl
+import android.view.SurfaceControlViewHost
+import android.view.View
+import android.view.WindowManager
+import androidx.test.filters.SmallTest
+import com.android.wm.shell.ShellTestCase
+import com.google.common.truth.Truth.assertThat
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertThrows
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mockito.mock
+import org.mockito.kotlin.spy
+import org.mockito.kotlin.verify
+
+
+/**
+ * Tests for [DefaultWindowDecorViewHost].
+ *
+ * Build/Install/Run:
+ * atest WMShellUnitTests:DefaultWindowDecorViewHostTest
+ */
+@SmallTest
+@TestableLooper.RunWithLooper
+@RunWith(AndroidTestingRunner::class)
+class DefaultWindowDecorViewHostTest : ShellTestCase() {
+
+    @Test
+    fun updateView_layoutInViewHost() = runTest {
+        val windowDecorViewHost = createDefaultViewHost()
+        val view = View(context)
+
+        windowDecorViewHost.updateView(
+            view = view,
+            attrs = WindowManager.LayoutParams(100, 100),
+            configuration = context.resources.configuration,
+            onDrawTransaction = null
+        )
+
+        assertThat(windowDecorViewHost.viewHost).isNotNull()
+        assertThat(windowDecorViewHost.viewHost!!.view).isEqualTo(view)
+    }
+
+    @Test
+    fun updateView_alreadyLaidOut_relayouts() = runTest {
+        val windowDecorViewHost = createDefaultViewHost()
+        val view = View(context)
+        windowDecorViewHost.updateView(
+            view = view,
+            attrs = WindowManager.LayoutParams(100, 100),
+            configuration = context.resources.configuration,
+            onDrawTransaction = null
+        )
+
+        val otherParams = WindowManager.LayoutParams(200, 200)
+        windowDecorViewHost.updateView(
+            view = view,
+            attrs = otherParams,
+            configuration = context.resources.configuration,
+            onDrawTransaction = null
+        )
+
+        assertThat(windowDecorViewHost.viewHost!!.view).isEqualTo(view)
+        assertThat(windowDecorViewHost.viewHost!!.view!!.layoutParams.width)
+            .isEqualTo(otherParams.width)
+    }
+
+    @Test
+    fun updateView_replacingView_throws() = runTest {
+        val windowDecorViewHost = createDefaultViewHost()
+        val view = View(context)
+        windowDecorViewHost.updateView(
+            view = view,
+            attrs = WindowManager.LayoutParams(100, 100),
+            configuration = context.resources.configuration,
+            onDrawTransaction = null
+        )
+
+        val otherView = View(context)
+        assertThrows(Exception::class.java) {
+            windowDecorViewHost.updateView(
+                view = otherView,
+                attrs = WindowManager.LayoutParams(100, 100),
+                configuration = context.resources.configuration,
+                onDrawTransaction = null
+            )
+        }
+    }
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    @Test
+    fun updateView_clearsPendingAsyncJob() = runTest {
+        val windowDecorViewHost = createDefaultViewHost()
+        val asyncView = View(context)
+        val syncView = View(context)
+        val asyncAttrs = WindowManager.LayoutParams(100, 100)
+        val syncAttrs = WindowManager.LayoutParams(200, 200)
+
+        windowDecorViewHost.updateViewAsync(
+            view = asyncView,
+            attrs = asyncAttrs,
+            configuration = context.resources.configuration,
+        )
+
+        // No view host yet, since the coroutine hasn't run.
+        assertThat(windowDecorViewHost.viewHost).isNull()
+
+        windowDecorViewHost.updateView(
+            view = syncView,
+            attrs = syncAttrs,
+            configuration = context.resources.configuration,
+            onDrawTransaction = null
+        )
+
+        // Would run coroutine if it hadn't been cancelled.
+        advanceUntilIdle()
+
+        assertThat(windowDecorViewHost.viewHost).isNotNull()
+        assertThat(windowDecorViewHost.viewHost!!.view).isNotNull()
+        // View host view/attrs should match the ones from the sync call, plus, since the
+        // sync/async were made with different views, if the job hadn't been cancelled there
+        // would've been an exception thrown as replacing views isn't allowed.
+        assertThat(windowDecorViewHost.viewHost!!.view).isEqualTo(syncView)
+        assertThat(windowDecorViewHost.viewHost!!.view!!.layoutParams.width)
+            .isEqualTo(syncAttrs.width)
+    }
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    @Test
+    fun updateViewAsync() = runTest {
+        val windowDecorViewHost = createDefaultViewHost()
+        val view = View(context)
+        val attrs = WindowManager.LayoutParams(100, 100)
+
+        windowDecorViewHost.updateViewAsync(
+            view = view,
+            attrs = attrs,
+            configuration = context.resources.configuration,
+        )
+
+        assertThat(windowDecorViewHost.viewHost).isNull()
+
+        advanceUntilIdle()
+
+        assertThat(windowDecorViewHost.viewHost).isNotNull()
+    }
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    @Test
+    fun updateViewAsync_clearsPendingAsyncJob() = runTest {
+        val windowDecorViewHost = createDefaultViewHost()
+
+        val view = View(context)
+        windowDecorViewHost.updateViewAsync(
+            view = view,
+            attrs = WindowManager.LayoutParams(100, 100),
+            configuration = context.resources.configuration,
+        )
+        val otherView = View(context)
+        windowDecorViewHost.updateViewAsync(
+            view = otherView,
+            attrs = WindowManager.LayoutParams(100, 100),
+            configuration = context.resources.configuration,
+        )
+
+        advanceUntilIdle()
+
+        assertThat(windowDecorViewHost.viewHost).isNotNull()
+        assertThat(windowDecorViewHost.viewHost!!.view).isNotNull()
+        assertThat(windowDecorViewHost.viewHost!!.view).isEqualTo(otherView)
+    }
+
+    @Test
+    fun release() = runTest {
+        val windowDecorViewHost = createDefaultViewHost()
+
+        val view = View(context)
+        windowDecorViewHost.updateView(
+            view = view,
+            attrs = WindowManager.LayoutParams(100, 100),
+            configuration = context.resources.configuration,
+            onDrawTransaction = null
+        )
+
+        val t = mock(SurfaceControl.Transaction::class.java)
+        windowDecorViewHost.release(t)
+
+        verify(windowDecorViewHost.viewHost!!).release()
+        verify(t).remove(windowDecorViewHost.surfaceControl)
+    }
+
+    private fun CoroutineScope.createDefaultViewHost() = DefaultWindowDecorViewHost(
+        context = context,
+        mainScope = this,
+        display = context.display,
+        surfaceControlViewHostFactory = { c, d, wwm, s ->
+            spy(SurfaceControlViewHost(c, d, wwm, s))
+        }
+    )
+}
\ No newline at end of file