Merge "[Divider] Add Operation to boost the decor surface" into main

5 files changed, 239 insertions, 34 deletions

diff --git a/core/java/android/window/TaskFragmentOperation.java b/core/java/android/window/TaskFragmentOperation.java
index 7b8cdff8e20b..7e77f150b63b 100644
--- a/core/java/android/window/TaskFragmentOperation.java
+++ b/core/java/android/window/TaskFragmentOperation.java
@@ -24,6 +24,7 @@ import android.os.Bundle;
 import android.os.IBinder;
 import android.os.Parcel;
 import android.os.Parcelable;
+import android.view.SurfaceControl;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -111,7 +112,8 @@ public final class TaskFragmentOperation implements Parcelable {
     /**
      * Creates a decor surface in the parent Task of the TaskFragment. The created decor surface
      * will be provided in {@link TaskFragmentTransaction#TYPE_TASK_FRAGMENT_PARENT_INFO_CHANGED}
-     * event callback.
+     * event callback. The decor surface can be used to draw the divider between TaskFragments or
+     * other decorations.
      */
     public static final int OP_TYPE_CREATE_TASK_FRAGMENT_DECOR_SURFACE = 14;
 
@@ -135,6 +137,15 @@ public final class TaskFragmentOperation implements Parcelable {
      */
     public static final int OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH = 17;
 
+    /**
+     * Sets whether the decor surface will be boosted. When not boosted, the decor surface is placed
+     * below any TaskFragments in untrusted mode or any activities with uid different from the
+     * TaskFragmentOrganizer uid and just above its owner TaskFragment; when boosted, the decor
+     * surface is placed above all the non-boosted windows in the Task, the content of these
+     * non-boosted windows will be hidden and inputs are disabled.
+     */
+    public static final int OP_TYPE_SET_DECOR_SURFACE_BOOSTED = 18;
+
     @IntDef(prefix = { "OP_TYPE_" }, value = {
             OP_TYPE_UNKNOWN,
             OP_TYPE_CREATE_TASK_FRAGMENT,
@@ -155,6 +166,7 @@ public final class TaskFragmentOperation implements Parcelable {
             OP_TYPE_REMOVE_TASK_FRAGMENT_DECOR_SURFACE,
             OP_TYPE_SET_DIM_ON_TASK,
             OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH,
+            OP_TYPE_SET_DECOR_SURFACE_BOOSTED,
     })
     @Retention(RetentionPolicy.SOURCE)
     public @interface OperationType {}
@@ -186,12 +198,18 @@ public final class TaskFragmentOperation implements Parcelable {
 
     private final boolean mMoveToBottomIfClearWhenLaunch;
 
+    private final boolean mBooleanValue;
+
+    @Nullable
+    private final SurfaceControl.Transaction mSurfaceTransaction;
+
     private TaskFragmentOperation(@OperationType int opType,
             @Nullable TaskFragmentCreationParams taskFragmentCreationParams,
             @Nullable IBinder activityToken, @Nullable Intent activityIntent,
             @Nullable Bundle bundle, @Nullable IBinder secondaryFragmentToken,
             @Nullable TaskFragmentAnimationParams animationParams,
-            boolean isolatedNav, boolean dimOnTask, boolean moveToBottomIfClearWhenLaunch) {
+            boolean isolatedNav, boolean dimOnTask, boolean moveToBottomIfClearWhenLaunch,
+            boolean booleanValue, @Nullable SurfaceControl.Transaction surfaceTransaction) {
         mOpType = opType;
         mTaskFragmentCreationParams = taskFragmentCreationParams;
         mActivityToken = activityToken;
@@ -202,6 +220,8 @@ public final class TaskFragmentOperation implements Parcelable {
         mIsolatedNav = isolatedNav;
         mDimOnTask = dimOnTask;
         mMoveToBottomIfClearWhenLaunch = moveToBottomIfClearWhenLaunch;
+        mBooleanValue = booleanValue;
+        mSurfaceTransaction = surfaceTransaction;
     }
 
     private TaskFragmentOperation(Parcel in) {
@@ -215,6 +235,8 @@ public final class TaskFragmentOperation implements Parcelable {
         mIsolatedNav = in.readBoolean();
         mDimOnTask = in.readBoolean();
         mMoveToBottomIfClearWhenLaunch = in.readBoolean();
+        mBooleanValue = in.readBoolean();
+        mSurfaceTransaction = in.readTypedObject(SurfaceControl.Transaction.CREATOR);
     }
 
     @Override
@@ -229,6 +251,8 @@ public final class TaskFragmentOperation implements Parcelable {
         dest.writeBoolean(mIsolatedNav);
         dest.writeBoolean(mDimOnTask);
         dest.writeBoolean(mMoveToBottomIfClearWhenLaunch);
+        dest.writeBoolean(mBooleanValue);
+        dest.writeTypedObject(mSurfaceTransaction, flags);
     }
 
     @NonNull
@@ -324,6 +348,22 @@ public final class TaskFragmentOperation implements Parcelable {
         return mMoveToBottomIfClearWhenLaunch;
     }
 
+    /** Returns the boolean value for this operation. */
+    public boolean getBooleanValue() {
+        return mBooleanValue;
+    }
+
+    /**
+     * Returns {@link SurfaceControl.Transaction} associated with this operation. Currently, this is
+     * only used by {@link TaskFragmentOperation#OP_TYPE_SET_DECOR_SURFACE_BOOSTED} to specify a
+     * {@link SurfaceControl.Transaction} that should be applied together with the transaction to
+     * change the decor surface layers.
+     */
+    @Nullable
+    public SurfaceControl.Transaction getSurfaceTransaction() {
+        return mSurfaceTransaction;
+    }
+
     @Override
     public String toString() {
         final StringBuilder sb = new StringBuilder();
@@ -349,6 +389,10 @@ public final class TaskFragmentOperation implements Parcelable {
         sb.append(", isolatedNav=").append(mIsolatedNav);
         sb.append(", dimOnTask=").append(mDimOnTask);
         sb.append(", moveToBottomIfClearWhenLaunch=").append(mMoveToBottomIfClearWhenLaunch);
+        sb.append(", booleanValue=").append(mBooleanValue);
+        if (mSurfaceTransaction != null) {
+            sb.append(", surfaceTransaction=").append(mSurfaceTransaction);
+        }
 
         sb.append('}');
         return sb.toString();
@@ -358,7 +402,7 @@ public final class TaskFragmentOperation implements Parcelable {
     public int hashCode() {
         return Objects.hash(mOpType, mTaskFragmentCreationParams, mActivityToken, mActivityIntent,
                 mBundle, mSecondaryFragmentToken, mAnimationParams, mIsolatedNav, mDimOnTask,
-                mMoveToBottomIfClearWhenLaunch);
+                mMoveToBottomIfClearWhenLaunch, mBooleanValue, mSurfaceTransaction);
     }
 
     @Override
@@ -376,7 +420,9 @@ public final class TaskFragmentOperation implements Parcelable {
                 && Objects.equals(mAnimationParams, other.mAnimationParams)
                 && mIsolatedNav == other.mIsolatedNav
                 && mDimOnTask == other.mDimOnTask
-                && mMoveToBottomIfClearWhenLaunch == other.mMoveToBottomIfClearWhenLaunch;
+                && mMoveToBottomIfClearWhenLaunch == other.mMoveToBottomIfClearWhenLaunch
+                && mBooleanValue == other.mBooleanValue
+                && Objects.equals(mSurfaceTransaction, other.mSurfaceTransaction);
     }
 
     @Override
@@ -414,6 +460,11 @@ public final class TaskFragmentOperation implements Parcelable {
 
         private boolean mMoveToBottomIfClearWhenLaunch;
 
+        private boolean mBooleanValue;
+
+        @Nullable
+        private SurfaceControl.Transaction mSurfaceTransaction;
+
         /**
          * @param opType the {@link OperationType} of this {@link TaskFragmentOperation}.
          */
@@ -505,13 +556,37 @@ public final class TaskFragmentOperation implements Parcelable {
         }
 
         /**
+         * Sets the boolean value for this operation.
+         * TODO(b/327338038) migrate other boolean values to use shared mBooleanValue
+         */
+        @NonNull
+        public Builder setBooleanValue(boolean booleanValue) {
+            mBooleanValue = booleanValue;
+            return this;
+        }
+
+        /**
+         * Sets {@link SurfaceControl.Transaction} associated with this operation. Currently, this
+         * is only used by {@link TaskFragmentOperation#OP_TYPE_SET_DECOR_SURFACE_BOOSTED} to
+         * specify a {@link SurfaceControl.Transaction} that should be applied together with the
+         * transaction to change the decor surface layers.
+         */
+        @NonNull
+        public Builder setSurfaceTransaction(
+                @Nullable SurfaceControl.Transaction surfaceTransaction) {
+            mSurfaceTransaction = surfaceTransaction;
+            return this;
+        }
+
+        /**
          * Constructs the {@link TaskFragmentOperation}.
          */
         @NonNull
         public TaskFragmentOperation build() {
             return new TaskFragmentOperation(mOpType, mTaskFragmentCreationParams, mActivityToken,
                     mActivityIntent, mBundle, mSecondaryFragmentToken, mAnimationParams,
-                    mIsolatedNav, mDimOnTask, mMoveToBottomIfClearWhenLaunch);
+                    mIsolatedNav, mDimOnTask, mMoveToBottomIfClearWhenLaunch, mBooleanValue,
+                    mSurfaceTransaction);
         }
     }
 }
diff --git a/services/core/java/com/android/server/wm/ActivityRecord.java b/services/core/java/com/android/server/wm/ActivityRecord.java
index 0069cdd1e4e8..6fa6957f2949 100644
--- a/services/core/java/com/android/server/wm/ActivityRecord.java
+++ b/services/core/java/com/android/server/wm/ActivityRecord.java
@@ -7786,8 +7786,11 @@ final class ActivityRecord extends WindowToken implements WindowManagerService.A
 
     @Override
     void prepareSurfaces() {
-        final boolean show = isVisible() || isAnimating(PARENTS,
-                ANIMATION_TYPE_APP_TRANSITION | ANIMATION_TYPE_RECENTS
+        final boolean show = (isVisible()
+                // Ensure that the activity content is hidden when the decor surface is boosted to
+                // prevent UI redressing attack.
+                && !getTask().isDecorSurfaceBoosted())
+                || isAnimating(PARENTS, ANIMATION_TYPE_APP_TRANSITION | ANIMATION_TYPE_RECENTS
                         | ANIMATION_TYPE_PREDICT_BACK);
 
         if (mSurfaceControl != null) {
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index d87e21c0ac92..55dc30cc37d5 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -3741,7 +3741,9 @@ class Task extends TaskFragment {
             wc.assignChildLayers(t);
             if (!wc.needsZBoost()) {
                 // Place the decor surface under any untrusted content.
-                if (mDecorSurfaceContainer != null && !decorSurfacePlaced
+                if (mDecorSurfaceContainer != null
+                        && !mDecorSurfaceContainer.mIsBoosted
+                        && !decorSurfacePlaced
                         && shouldPlaceDecorSurfaceBelowContainer(wc)) {
                     mDecorSurfaceContainer.assignLayer(t, layer++);
                     decorSurfacePlaced = true;
@@ -3760,7 +3762,9 @@ class Task extends TaskFragment {
                 }
 
                 // Place the decor surface just above the owner TaskFragment.
-                if (mDecorSurfaceContainer != null && !decorSurfacePlaced
+                if (mDecorSurfaceContainer != null
+                        && !mDecorSurfaceContainer.mIsBoosted
+                        && !decorSurfacePlaced
                         && wc == mDecorSurfaceContainer.mOwnerTaskFragment) {
                     mDecorSurfaceContainer.assignLayer(t, layer++);
                     decorSurfacePlaced = true;
@@ -3768,10 +3772,10 @@ class Task extends TaskFragment {
             }
         }
 
-        // If not placed yet, the decor surface should be on top of all non-boosted children.
-        if (mDecorSurfaceContainer != null && !decorSurfacePlaced) {
+        // Boost the decor surface above other non-boosted windows if requested. The cover surface
+        // will ensure that the content of the windows below are invisible.
+        if (mDecorSurfaceContainer != null && mDecorSurfaceContainer.mIsBoosted) {
             mDecorSurfaceContainer.assignLayer(t, layer++);
-            decorSurfacePlaced = true;
         }
 
         for (int j = 0; j < mChildren.size(); ++j) {
@@ -3796,6 +3800,24 @@ class Task extends TaskFragment {
         return !isOwnActivity && !isTrustedTaskFragment;
     }
 
+    void setDecorSurfaceBoosted(
+            @NonNull TaskFragment ownerTaskFragment,
+            boolean isBoosted,
+            @Nullable SurfaceControl.Transaction clientTransaction) {
+        if (mDecorSurfaceContainer == null
+                || mDecorSurfaceContainer.mOwnerTaskFragment != ownerTaskFragment) {
+            return;
+        }
+        mDecorSurfaceContainer.setBoosted(isBoosted, clientTransaction);
+        // scheduleAnimation() is called inside assignChildLayers(), which ensures that child
+        // surface visibility is updated with prepareSurfaces()
+        assignChildLayers();
+    }
+
+    boolean isDecorSurfaceBoosted() {
+        return mDecorSurfaceContainer != null && mDecorSurfaceContainer.mIsBoosted;
+    }
+
     boolean isTaskId(int taskId) {
         return mTaskId == taskId;
     }
@@ -6796,14 +6818,35 @@ class Task extends TaskFragment {
     }
 
     /**
-     * A decor surface that is requested by a {@code TaskFragmentOrganizer} which will be placed
-     * below children windows except for own Activities and TaskFragment in fully trusted mode.
+     * A class managing the decor surface.
+     *
+     * A decor surface is requested by a {@link TaskFragmentOrganizer} and is placed below children
+     * windows in the Task except for own Activities and TaskFragments in fully trusted mode. The
+     * decor surface is created and shared with the client app with
+     * {@link android.window.TaskFragmentOperation#OP_TYPE_CREATE_TASK_FRAGMENT_DECOR_SURFACE} and
+     * be removed with
+     * {@link android.window.TaskFragmentOperation#OP_TYPE_REMOVE_TASK_FRAGMENT_DECOR_SURFACE}.
+     *
+     * When boosted with
+     * {@link android.window.TaskFragmentOperation#OP_TYPE_SET_DECOR_SURFACE_BOOSTED}, the decor
+     * surface is placed above all non-boosted windows in the Task, but all the content below it
+     * will be hidden to prevent UI redressing attacks. This can be used by the draggable
+     * divider between {@link TaskFragment}s where veils are drawn on the decor surface while
+     * dragging to indicate new bounds.
      */
     @VisibleForTesting
     class DecorSurfaceContainer {
+
+        // The container surface is the parent of the decor surface. The container surface
+        // should NEVER be shared with the client. It is used to ensure that the decor surface has
+        // a z-order in the Task that is managed by WM core and cannot be updated by the client
+        // process.
         @VisibleForTesting
         @NonNull final SurfaceControl mContainerSurface;
 
+        // The decor surface is shared with the client process owning the
+        // {@link TaskFragmentOrganizer}. It can be used to draw the divider between TaskFragments
+        // or other decorations.
         @VisibleForTesting
         @NonNull final SurfaceControl mDecorSurface;
 
@@ -6812,12 +6855,18 @@ class Task extends TaskFragment {
         @VisibleForTesting
         @NonNull TaskFragment mOwnerTaskFragment;
 
+        private boolean mIsBoosted;
+
+        // The surface transactions that will be applied when the layer is reassigned.
+        @NonNull private final List<SurfaceControl.Transaction> mPendingClientTransactions =
+                new ArrayList<>();
+
         private DecorSurfaceContainer(@NonNull TaskFragment initialOwner) {
             mOwnerTaskFragment = initialOwner;
             mContainerSurface = makeSurface().setContainerLayer()
                     .setParent(mSurfaceControl)
                     .setName(mSurfaceControl + " - decor surface container")
-                    .setEffectLayer()
+                    .setContainerLayer()
                     .setHidden(false)
                     .setCallsite("Task.DecorSurfaceContainer")
                     .build();
@@ -6830,14 +6879,28 @@ class Task extends TaskFragment {
                     .build();
         }
 
+        private void setBoosted(
+                boolean isBoosted, @Nullable SurfaceControl.Transaction clientTransaction) {
+            mIsBoosted = isBoosted;
+            // The client transaction will be applied together with the next assignLayer.
+            if (clientTransaction != null) {
+                mDecorSurfaceContainer.mPendingClientTransactions.add(clientTransaction);
+            }
+        }
+
         private void assignLayer(@NonNull SurfaceControl.Transaction t, int layer) {
             t.setLayer(mContainerSurface, layer);
             t.setVisibility(mContainerSurface, mOwnerTaskFragment.isVisible());
+            for (int i = 0; i < mPendingClientTransactions.size(); i++) {
+                t.merge(mPendingClientTransactions.get(i));
+            }
+            mPendingClientTransactions.clear();
         }
 
         private void release() {
-            mDecorSurface.release();
-            mContainerSurface.release();
+            getSyncTransaction()
+                    .remove(mDecorSurface)
+                    .remove(mContainerSurface);
         }
     }
 }
diff --git a/services/core/java/com/android/server/wm/WindowOrganizerController.java b/services/core/java/com/android/server/wm/WindowOrganizerController.java
index a63e106beb55..7e6f5ac7497e 100644
--- a/services/core/java/com/android/server/wm/WindowOrganizerController.java
+++ b/services/core/java/com/android/server/wm/WindowOrganizerController.java
@@ -34,6 +34,7 @@ import static android.window.TaskFragmentOperation.OP_TYPE_REQUEST_FOCUS_ON_TASK
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_ADJACENT_TASK_FRAGMENTS;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_ANIMATION_PARAMS;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_COMPANION_TASK_FRAGMENT;
+import static android.window.TaskFragmentOperation.OP_TYPE_SET_DECOR_SURFACE_BOOSTED;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_DIM_ON_TASK;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_ISOLATED_NAVIGATION;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH;
@@ -124,6 +125,7 @@ import com.android.internal.protolog.common.ProtoLog;
 import com.android.internal.util.ArrayUtils;
 import com.android.server.LocalServices;
 import com.android.server.pm.LauncherAppsService.LauncherAppsServiceInternal;
+import com.android.window.flags.Flags;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -1557,13 +1559,11 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
                 break;
             }
             case OP_TYPE_CREATE_TASK_FRAGMENT_DECOR_SURFACE: {
-                final Task task = taskFragment.getTask();
-                task.moveOrCreateDecorSurfaceFor(taskFragment);
+                taskFragment.getTask().moveOrCreateDecorSurfaceFor(taskFragment);
                 break;
             }
             case OP_TYPE_REMOVE_TASK_FRAGMENT_DECOR_SURFACE: {
-                final Task task = taskFragment.getTask();
-                task.removeDecorSurface();
+                taskFragment.getTask().removeDecorSurface();
                 break;
             }
             case OP_TYPE_SET_DIM_ON_TASK: {
@@ -1577,6 +1577,23 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
                         operation.isMoveToBottomIfClearWhenLaunch());
                 break;
             }
+            case OP_TYPE_SET_DECOR_SURFACE_BOOSTED: {
+                if (Flags.activityEmbeddingInteractiveDividerFlag()) {
+                    final SurfaceControl.Transaction clientTransaction =
+                            operation.getSurfaceTransaction();
+                    if (clientTransaction != null) {
+                        // Sanitize the client transaction. sanitize() silently removes invalid
+                        // operations and does not throw or provide signal about whether there are
+                        // any invalid operations.
+                        clientTransaction.sanitize(caller.mPid, caller.mUid);
+                    }
+                    taskFragment.getTask().setDecorSurfaceBoosted(
+                            taskFragment,
+                            operation.getBooleanValue() /* isBoosted */,
+                            clientTransaction);
+                }
+                break;
+            }
         }
         return effects;
     }
@@ -1616,19 +1633,6 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
             return false;
         }
 
-        // TODO (b/293654166) remove the decor surface checks once we clear security reviews
-        if ((opType == OP_TYPE_CREATE_TASK_FRAGMENT_DECOR_SURFACE
-                || opType == OP_TYPE_REMOVE_TASK_FRAGMENT_DECOR_SURFACE)
-                && !mTaskFragmentOrganizerController.isSystemOrganizer(organizer.asBinder())) {
-            final Throwable exception = new SecurityException(
-                    "Only a system organizer can perform OP_TYPE_CREATE_TASK_FRAGMENT_DECOR_SURFACE"
-                            + " or OP_TYPE_REMOVE_TASK_FRAGMENT_DECOR_SURFACE."
-            );
-            sendTaskFragmentOperationFailure(organizer, errorCallbackToken, taskFragment,
-                    opType, exception);
-            return false;
-        }
-
         if ((opType == OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH)
                 && !mTaskFragmentOrganizerController.isSystemOrganizer(organizer.asBinder())) {
             final Throwable exception = new SecurityException(
diff --git a/services/tests/wmtests/src/com/android/server/wm/TaskTests.java b/services/tests/wmtests/src/com/android/server/wm/TaskTests.java
index 961fdfb14bf3..f506e9fbbb14 100644
--- a/services/tests/wmtests/src/com/android/server/wm/TaskTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/TaskTests.java
@@ -1823,6 +1823,66 @@ public class TaskTests extends WindowTestsBase {
     }
 
     @Test
+    public void testAssignChildLayers_boostedDecorSurfacePlacement() {
+        final TaskFragmentOrganizer organizer = new TaskFragmentOrganizer(Runnable::run);
+        final Task task =  new TaskBuilder(mSupervisor).setCreateActivity(true).build();
+        final ActivityRecord unembeddedActivity = task.getTopMostActivity();
+
+        final TaskFragment fragment1 = createTaskFragmentWithEmbeddedActivity(task, organizer);
+        final TaskFragment fragment2 = createTaskFragmentWithEmbeddedActivity(task, organizer);
+        final SurfaceControl.Transaction t = task.getSyncTransaction();
+        final SurfaceControl.Transaction clientTransaction = mock(SurfaceControl.Transaction.class);
+
+        doNothing().when(task).sendTaskFragmentParentInfoChangedIfNeeded();
+        spyOn(unembeddedActivity);
+        spyOn(fragment1);
+        spyOn(fragment2);
+
+        doReturn(true).when(unembeddedActivity).isUid(task.effectiveUid);
+        doReturn(true).when(fragment1).isAllowedToBeEmbeddedInTrustedMode();
+        doReturn(false).when(fragment2).isAllowedToBeEmbeddedInTrustedMode();
+        doReturn(true).when(fragment1).isVisible();
+
+        task.moveOrCreateDecorSurfaceFor(fragment1);
+
+        clearInvocations(t);
+        clearInvocations(unembeddedActivity);
+        clearInvocations(fragment1);
+        clearInvocations(fragment2);
+
+        // The decor surface should be placed above all the windows when boosted and the cover
+        // surface should show.
+        task.setDecorSurfaceBoosted(fragment1, true /* isBoosted */, clientTransaction);
+
+        verify(unembeddedActivity).assignLayer(t, 0);
+        verify(fragment1).assignLayer(t, 1);
+        verify(fragment2).assignLayer(t, 2);
+        verify(t).setLayer(task.mDecorSurfaceContainer.mContainerSurface, 3);
+
+        verify(t).setVisibility(task.mDecorSurfaceContainer.mContainerSurface, true);
+        verify(t).merge(clientTransaction);
+
+        clearInvocations(t);
+        clearInvocations(unembeddedActivity);
+        clearInvocations(fragment1);
+        clearInvocations(fragment2);
+
+        // The decor surface should be placed just above the owner TaskFragment and the cover
+        // surface should hide.
+        task.moveOrCreateDecorSurfaceFor(fragment1);
+        task.setDecorSurfaceBoosted(fragment1, false /* isBoosted */, clientTransaction);
+
+        verify(unembeddedActivity).assignLayer(t, 0);
+        verify(fragment1).assignLayer(t, 1);
+        verify(t).setLayer(task.mDecorSurfaceContainer.mContainerSurface, 2);
+        verify(fragment2).assignLayer(t, 3);
+
+        verify(t).setVisibility(task.mDecorSurfaceContainer.mContainerSurface, true);
+        verify(t).merge(clientTransaction);
+
+    }
+
+    @Test
     public void testMoveTaskFragmentsToBottomIfNeeded() {
         final TaskFragmentOrganizer organizer = new TaskFragmentOrganizer(Runnable::run);
         final Task task = new TaskBuilder(mSupervisor).setCreateActivity(true).build();