diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index 132e486..882d5c7 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -37,7 +37,6 @@
 import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import static android.app.WindowConfiguration.WINDOWING_MODE_PINNED;
 import static android.app.WindowConfiguration.WINDOWING_MODE_SPLIT_SCREEN_PRIMARY;
-import static android.app.WindowConfiguration.WINDOWING_MODE_SPLIT_SCREEN_SECONDARY;
 import static android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED;
 import static android.content.Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
@@ -229,6 +228,7 @@
 import android.view.IRecentsAnimationRunner;
 import android.view.RemoteAnimationAdapter;
 import android.view.RemoteAnimationDefinition;
+import android.view.WindowContainerTransaction;
 import android.view.WindowManager;
 
 import com.android.internal.R;
@@ -2269,6 +2269,9 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
+                if (WindowConfiguration.isSplitScreenWindowingMode(windowingMode)) {
+                    return setTaskWindowingModeSplitScreen(taskId, windowingMode, toTop);
+                }
                 final Task task = mRootWindowContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_ONLY);
                 if (task == null) {
@@ -2286,10 +2289,16 @@
                 }
 
                 final ActivityStack stack = task.getStack();
+                // Convert some windowing-mode changes into root-task reparents for split-screen.
+                if (stack.getTile() != null) {
+                    stack.getDisplay().onSplitScreenModeDismissed();
+                }
                 if (toTop) {
                     stack.moveToFront("setTaskWindowingMode", task);
                 }
                 stack.setWindowingMode(windowingMode);
+                stack.getDisplay().ensureActivitiesVisible(null, 0, PRESERVE_WINDOWS,
+                        true /* notifyClients */);
                 return true;
             } finally {
                 Binder.restoreCallingIdentity(ident);
@@ -2719,36 +2728,8 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
-                if (isInLockTaskMode()) {
-                    Slog.w(TAG, "setTaskWindowingModeSplitScreenPrimary: Is in lock task mode="
-                            + getLockTaskModeState());
-                    return false;
-                }
-
-                final Task task = mRootWindowContainer.anyTaskForId(taskId,
-                        MATCH_TASK_IN_STACKS_ONLY);
-                if (task == null) {
-                    Slog.w(TAG, "setTaskWindowingModeSplitScreenPrimary: No task for id=" + taskId);
-                    return false;
-                }
-                if (!task.isActivityTypeStandardOrUndefined()) {
-                    throw new IllegalArgumentException("setTaskWindowingMode: Attempt to move"
-                            + " non-standard task " + taskId + " to split-screen windowing mode");
-                }
-
-                if (DEBUG_STACK) Slog.d(TAG_STACK,
-                        "setTaskWindowingModeSplitScreenPrimary: moving task=" + taskId
-                                + " to createMode=" + createMode + " toTop=" + toTop);
-                mWindowManager.setDockedStackCreateStateLocked(createMode, initialBounds);
-                final int windowingMode = task.getWindowingMode();
-                final ActivityStack stack = task.getStack();
-                if (toTop) {
-                    stack.moveToFront("setTaskWindowingModeSplitScreenPrimary", task);
-                }
-                stack.setWindowingMode(WINDOWING_MODE_SPLIT_SCREEN_PRIMARY, animate, showRecents,
-                        false /* enteringSplitScreenMode */, false /* deferEnsuringVisibility */,
-                        false /* creating */);
-                return windowingMode != task.getWindowingMode();
+                return setTaskWindowingModeSplitScreen(taskId, WINDOWING_MODE_SPLIT_SCREEN_PRIMARY,
+                        toTop);
             } finally {
                 Binder.restoreCallingIdentity(ident);
             }
@@ -2756,6 +2737,49 @@
     }
 
     /**
+     * Moves the specified task into a split-screen tile.
+     */
+    private boolean setTaskWindowingModeSplitScreen(int taskId, int windowingMode, boolean toTop) {
+        if (!WindowConfiguration.isSplitScreenWindowingMode(windowingMode)) {
+            throw new IllegalArgumentException("Calling setTaskWindowingModeSplitScreen with non"
+                    + "split-screen mode: " + windowingMode);
+        }
+        if (isInLockTaskMode()) {
+            Slog.w(TAG, "setTaskWindowingModeSplitScreen: Is in lock task mode="
+                    + getLockTaskModeState());
+            return false;
+        }
+
+        final Task task = mRootWindowContainer.anyTaskForId(taskId,
+                MATCH_TASK_IN_STACKS_ONLY);
+        if (task == null) {
+            Slog.w(TAG, "setTaskWindowingModeSplitScreenPrimary: No task for id=" + taskId);
+            return false;
+        }
+        if (!task.isActivityTypeStandardOrUndefined()) {
+            throw new IllegalArgumentException("setTaskWindowingMode: Attempt to move"
+                    + " non-standard task " + taskId + " to split-screen windowing mode");
+        }
+
+        final int prevMode = task.getWindowingMode();
+        final ActivityStack stack = task.getStack();
+        TaskTile tile = null;
+        for (int i = stack.getDisplay().getStackCount() - 1; i >= 0; --i) {
+            tile = stack.getDisplay().getStackAt(i).asTile();
+            if (tile != null && tile.getWindowingMode() == WINDOWING_MODE_SPLIT_SCREEN_PRIMARY) {
+                break;
+            }
+        }
+        if (tile == null) {
+            throw new IllegalStateException("Can't enter split without associated tile");
+        }
+        WindowContainerTransaction wct = new WindowContainerTransaction();
+        wct.reparent(stack.mRemoteToken, tile.mRemoteToken, toTop);
+        mTaskOrganizerController.applyContainerTransaction(wct, null);
+        return prevMode != task.getWindowingMode();
+    }
+
+    /**
      * Removes stacks in the input windowing modes from the system if they are of activity type
      * ACTIVITY_TYPE_STANDARD or ACTIVITY_TYPE_UNDEFINED
      */
@@ -3963,46 +3987,6 @@
     }
 
     /**
-     * Dismisses split-screen multi-window mode.
-     * @param toTop If true the current primary split-screen stack will be placed or left on top.
-     */
-    @Override
-    public void dismissSplitScreenMode(boolean toTop) {
-        enforceCallerIsRecentsOrHasPermission(
-                MANAGE_ACTIVITY_STACKS, "dismissSplitScreenMode()");
-        final long ident = Binder.clearCallingIdentity();
-        try {
-            synchronized (mGlobalLock) {
-                final ActivityStack stack =
-                        mRootWindowContainer.getDefaultDisplay().getRootSplitScreenPrimaryTask();
-                if (stack == null) {
-                    Slog.w(TAG, "dismissSplitScreenMode: primary split-screen stack not found.");
-                    return;
-                }
-
-                if (toTop) {
-                    // Caller wants the current split-screen primary stack to be the top stack after
-                    // it goes fullscreen, so move it to the front.
-                    stack.moveToFront("dismissSplitScreenMode");
-                } else {
-                    // In this case the current split-screen primary stack shouldn't be the top
-                    // stack after it goes fullscreen, so we move the focus to the top-most
-                    // split-screen secondary stack next to it.
-                    final ActivityStack otherStack = stack.getDisplay().getTopStackInWindowingMode(
-                            WINDOWING_MODE_SPLIT_SCREEN_SECONDARY);
-                    if (otherStack != null) {
-                        otherStack.moveToFront("dismissSplitScreenMode_other");
-                    }
-                }
-
-                stack.setWindowingMode(WINDOWING_MODE_UNDEFINED);
-            }
-        } finally {
-            Binder.restoreCallingIdentity(ident);
-        }
-    }
-
-    /**
      * Dismisses Pip
      * @param animate True if the dismissal should be animated.
      * @param animationDuration The duration of the resize animation in milliseconds or -1 if the