Rework stack Z-ordering promotion.

Down-boost home stack instead of up-boosting docked stack. This means
we don't have to do any assistant stack boosting so we wont have issues
with activities not being able to show on top of the assistant.

Change-Id: Iedef49a56a25fe0c6c26bfe4ef5194bcd8159c37
Fixes: 70318142
Fixes: 70675228
Fixes: 70178829
Fixes: 69553456
Fixes: 70178829
Test: Manual. ZOrderingTests. go/wm-smoke

diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index a8e00dd..d55ebe4 100644 (file)
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -49,6 +49,7 @@ import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_KEYGUARD;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_STARTING;
 import static android.view.WindowManager.LayoutParams.TYPE_BOOT_PROGRESS;
+import static android.view.WindowManager.LayoutParams.TYPE_DOCK_DIVIDER;
 import static android.view.WindowManager.LayoutParams.TYPE_DRAWN_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_DREAM;
 import static android.view.WindowManager.LayoutParams.TYPE_INPUT_METHOD;
@@ -3173,6 +3174,21 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
          */
         SurfaceControl mAppAnimationLayer = null;
 
+        /**
+         * Given that the split-screen divider does not have an AppWindowToken, it
+         * will have to live inside of a "NonAppWindowContainer", in particular
+         * {@link DisplayContent#mAboveAppWindowsContainers}. However, in visual Z order
+         * it will need to be interleaved with some of our children, appearing on top of
+         * both docked stacks but underneath any assistant stacks.
+         *
+         * To solve this problem we have this anchor control, which will always exist so
+         * we can always assign it the correct value in our {@link #assignChildLayers}.
+         * Likewise since it always exists, {@link AboveAppWindowContainers} can always
+         * assign the divider a layer relative to it. This way we prevent linking lifecycle
+         * events between the two containers.
+         */
+        SurfaceControl mSplitScreenDividerAnchor = null;
+
         // Cached reference to some special stacks we tend to get a lot so we don't need to loop
         // through the list to find them.
         private TaskStack mHomeStack = null;
@@ -3489,37 +3505,39 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
 
         @Override
         void assignChildLayers(SurfaceControl.Transaction t) {
-            int layer = 0;
 
-            // We allow stacks to change visual order from the AM specified order due to
-            // Z-boosting during animations. However we must take care to ensure TaskStacks
-            // which are marked as alwaysOnTop remain that way.
-            for (int i = 0; i < mChildren.size(); i++) {
-                final TaskStack s = mChildren.get(i);
-                s.assignChildLayers();
-                if (!s.needsZBoost() && !s.isAlwaysOnTop()) {
-                    s.assignLayer(t, layer++);
+            final int HOME_STACK_STATE = 0;
+            final int NORMAL_STACK_STATE = 1;
+            final int ALWAYS_ON_TOP_STATE = 2;
+
+            int layer = 0;
+            for (int state = 0; state <= ALWAYS_ON_TOP_STATE; state++) {
+                for (int i = 0; i < mChildren.size(); i++) {
+                    final TaskStack s = mChildren.get(i);
+                    if (state == HOME_STACK_STATE && s.isActivityTypeHome()) {
+                        s.assignLayer(t, layer++);
+                    } else if (state == NORMAL_STACK_STATE && !s.isActivityTypeHome()
+                            && !s.isAlwaysOnTop()) {
+                        s.assignLayer(t, layer++);
+                        if (s.inSplitScreenWindowingMode() && mSplitScreenDividerAnchor != null) {
+                            t.setLayer(mSplitScreenDividerAnchor, layer++);
+                        }
+                    } else if (state == ALWAYS_ON_TOP_STATE && s.isAlwaysOnTop()) {
+                        s.assignLayer(t, layer++);
+                    }
                 }
-            }
-            for (int i = 0; i < mChildren.size(); i++) {
-                final TaskStack s = mChildren.get(i);
-                if (s.needsZBoost() && !s.isAlwaysOnTop()) {
-                    s.assignLayer(t, layer++);
+                // The appropriate place for App-Transitions to occur is right
+                // above all other animations but still below things in the Picture-and-Picture
+                // windowing mode.
+                if (state == NORMAL_STACK_STATE && mAppAnimationLayer != null) {
+                    t.setLayer(mAppAnimationLayer, layer++);
                 }
             }
             for (int i = 0; i < mChildren.size(); i++) {
                 final TaskStack s = mChildren.get(i);
-                if (s.isAlwaysOnTop()) {
-                    s.assignLayer(t, layer++);
-                }
+                s.assignChildLayers(t);
             }
 
-            // The appropriate place for App-Transitions to occur is right
-            // above all other animations but still below things in the Picture-and-Picture
-            // windowing mode.
-            if (mAppAnimationLayer != null) {
-                t.setLayer(mAppAnimationLayer, layer++);
-            }
         }
 
         @Override
@@ -3527,6 +3545,10 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
             return mAppAnimationLayer;
         }
 
+        SurfaceControl getSplitScreenDividerAnchor() {
+            return mSplitScreenDividerAnchor;
+        }
+
         @Override
         void onParentSet() {
             super.onParentSet();
@@ -3534,11 +3556,18 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
                 mAppAnimationLayer = makeChildSurface(null)
                         .setName("animationLayer")
                         .build();
-                getPendingTransaction().show(mAppAnimationLayer);
+                mSplitScreenDividerAnchor = makeChildSurface(null)
+                        .setName("splitScreenDividerAnchor")
+                        .build();
+                getPendingTransaction()
+                        .show(mAppAnimationLayer)
+                        .show(mSplitScreenDividerAnchor);
                 scheduleAnimation();
             } else {
                 mAppAnimationLayer.destroy();
                 mAppAnimationLayer = null;
+                mSplitScreenDividerAnchor.destroy();
+                mSplitScreenDividerAnchor = null;
             }
         }
     }
@@ -3553,6 +3582,12 @@ class DisplayContent extends WindowContainer<DisplayContent.DisplayChildWindowCo
                     && imeContainer.getSurfaceControl() != null;
             for (int j = 0; j < mChildren.size(); ++j) {
                 final WindowToken wt = mChildren.get(j);
+
+                // See {@link mSplitScreenDividerAnchor}
+                if (wt.windowType == TYPE_DOCK_DIVIDER) {
+                    wt.assignRelativeLayer(t, mTaskStackContainers.getSplitScreenDividerAnchor(), 1);
+                    continue;
+                }
                 wt.assignLayer(t, j);
                 wt.assignChildLayers(t);
 

diff --git a/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java b/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java
index 6468763..5f44fb6 100644 (file)
--- a/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java
+++ b/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java
@@ -17,14 +17,17 @@
 package com.android.server.wm;
 
 import static android.app.WindowConfiguration.ACTIVITY_TYPE_ASSISTANT;
+import static android.app.WindowConfiguration.ACTIVITY_TYPE_HOME;
 import static android.app.WindowConfiguration.ACTIVITY_TYPE_STANDARD;
 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.view.WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA_OVERLAY;
 import static android.view.WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
+import static android.view.WindowManager.LayoutParams.TYPE_DOCK_DIVIDER;
 import static android.view.WindowManager.LayoutParams.TYPE_NAVIGATION_BAR_PANEL;
 import static android.view.WindowManager.LayoutParams.TYPE_STATUS_BAR_PANEL;
 import static android.view.WindowManager.LayoutParams.TYPE_STATUS_BAR_SUB_PANEL;
@@ -74,11 +77,11 @@ public class ZOrderingTests extends WindowTestsBase {
             return super.setRelativeLayer(sc, relativeTo, layer);
         }
 
-        int getLayer(SurfaceControl sc) {
+        private int getLayer(SurfaceControl sc) {
             return mLayersForControl.getOrDefault(sc, 0);
         }
 
-        SurfaceControl getRelativeLayer(SurfaceControl sc) {
+        private SurfaceControl getRelativeLayer(SurfaceControl sc) {
             return mRelativeLayersForControl.get(sc);
         }
     };
@@ -146,8 +149,9 @@ public class ZOrderingTests extends WindowTestsBase {
         return p;
     }
 
-    void assertZOrderGreaterThan(LayerRecordingTransaction t,
-            SurfaceControl left, SurfaceControl right) throws Exception {
+
+    void assertZOrderGreaterThan(LayerRecordingTransaction t, SurfaceControl left,
+            SurfaceControl right) throws Exception {
         final LinkedList<SurfaceControl> leftParentChain = getAncestors(t, left);
         final LinkedList<SurfaceControl> rightParentChain = getAncestors(t, right);
 
@@ -171,9 +175,12 @@ public class ZOrderingTests extends WindowTestsBase {
         }
     }
 
-    void assertWindowLayerGreaterThan(LayerRecordingTransaction t,
-            WindowState left, WindowState right) throws Exception {
-        assertZOrderGreaterThan(t, left.getSurfaceControl(), right.getSurfaceControl());
+    void assertWindowHigher(WindowState left, WindowState right) throws Exception {
+        assertZOrderGreaterThan(mTransaction, left.getSurfaceControl(), right.getSurfaceControl());
+    }
+
+    WindowState createWindow(String name) {
+        return createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, name);
     }
 
     @Test
@@ -184,38 +191,37 @@ public class ZOrderingTests extends WindowTestsBase {
         // The Ime has an higher base layer than app windows and lower base layer than system
         // windows, so it should be above app windows and below system windows if there isn't an IME
         // target.
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mChildAppWindowAbove);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mAppWindow);
-        assertWindowLayerGreaterThan(mTransaction, mNavBarWindow, mImeWindow);
-        assertWindowLayerGreaterThan(mTransaction, mStatusBarWindow, mImeWindow);
+        assertWindowHigher(mImeWindow, mChildAppWindowAbove);
+        assertWindowHigher(mImeWindow, mAppWindow);
+        assertWindowHigher(mNavBarWindow, mImeWindow);
+        assertWindowHigher(mStatusBarWindow, mImeWindow);
 
         // And, IME dialogs should always have an higher layer than the IME.
-        assertWindowLayerGreaterThan(mTransaction, mImeDialogWindow, mImeWindow);
+        assertWindowHigher(mImeDialogWindow, mImeWindow);
     }
 
     @Test
     public void testAssignWindowLayers_ForImeWithAppTarget() throws Exception {
-        final WindowState imeAppTarget =
-                createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, "imeAppTarget");
+        final WindowState imeAppTarget = createWindow("imeAppTarget");
         sWm.mInputMethodTarget = imeAppTarget;
+
         mDisplayContent.assignChildLayers(mTransaction);
 
         // Ime should be above all app windows and below system windows if it is targeting an app
         // window.
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, imeAppTarget);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mChildAppWindowAbove);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mAppWindow);
-        assertWindowLayerGreaterThan(mTransaction, mNavBarWindow, mImeWindow);
-        assertWindowLayerGreaterThan(mTransaction, mStatusBarWindow, mImeWindow);
+        assertWindowHigher(mImeWindow, imeAppTarget);
+        assertWindowHigher(mImeWindow, mChildAppWindowAbove);
+        assertWindowHigher(mImeWindow, mAppWindow);
+        assertWindowHigher(mNavBarWindow, mImeWindow);
+        assertWindowHigher(mStatusBarWindow, mImeWindow);
 
         // And, IME dialogs should always have an higher layer than the IME.
-        assertWindowLayerGreaterThan(mTransaction, mImeDialogWindow, mImeWindow);
+        assertWindowHigher(mImeDialogWindow, mImeWindow);
     }
 
     @Test
     public void testAssignWindowLayers_ForImeWithAppTargetWithChildWindows() throws Exception {
-        final WindowState imeAppTarget =
-                createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, "imeAppTarget");
+        final WindowState imeAppTarget = createWindow("imeAppTarget");
         final WindowState imeAppTargetChildAboveWindow = createWindow(imeAppTarget,
                 TYPE_APPLICATION_ATTACHED_DIALOG, imeAppTarget.mToken,
                 "imeAppTargetChildAboveWindow");
@@ -228,41 +234,38 @@ public class ZOrderingTests extends WindowTestsBase {
 
         // Ime should be above all app windows except for child windows that are z-ordered above it
         // and below system windows if it is targeting an app window.
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, imeAppTarget);
-        assertWindowLayerGreaterThan(mTransaction, imeAppTargetChildAboveWindow, mImeWindow);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mChildAppWindowAbove);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mAppWindow);
-        assertWindowLayerGreaterThan(mTransaction, mNavBarWindow, mImeWindow);
-        assertWindowLayerGreaterThan(mTransaction, mStatusBarWindow, mImeWindow);
+        assertWindowHigher(mImeWindow, imeAppTarget);
+        assertWindowHigher(imeAppTargetChildAboveWindow, mImeWindow);
+        assertWindowHigher(mImeWindow, mChildAppWindowAbove);
+        assertWindowHigher(mImeWindow, mAppWindow);
+        assertWindowHigher(mNavBarWindow, mImeWindow);
+        assertWindowHigher(mStatusBarWindow, mImeWindow);
 
         // And, IME dialogs should always have an higher layer than the IME.
-        assertWindowLayerGreaterThan(mTransaction, mImeDialogWindow, mImeWindow);
+        assertWindowHigher(mImeDialogWindow, mImeWindow);
     }
 
     @Test
     public void testAssignWindowLayers_ForImeWithAppTargetAndAppAbove() throws Exception {
-        final WindowState appBelowImeTarget =
-                createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, "appBelowImeTarget");
-        final WindowState imeAppTarget =
-                createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, "imeAppTarget");
-        final WindowState appAboveImeTarget =
-                createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, "appAboveImeTarget");
+        final WindowState appBelowImeTarget = createWindow("appBelowImeTarget");
+        final WindowState imeAppTarget = createWindow("imeAppTarget");
+        final WindowState appAboveImeTarget = createWindow("appAboveImeTarget");
 
         sWm.mInputMethodTarget = imeAppTarget;
         mDisplayContent.assignChildLayers(mTransaction);
 
         // Ime should be above all app windows except for non-fullscreen app window above it and
         // below system windows if it is targeting an app window.
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, imeAppTarget);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, appBelowImeTarget);
-        assertWindowLayerGreaterThan(mTransaction, appAboveImeTarget, mImeWindow);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mChildAppWindowAbove);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mAppWindow);
-        assertWindowLayerGreaterThan(mTransaction, mNavBarWindow, mImeWindow);
-        assertWindowLayerGreaterThan(mTransaction, mStatusBarWindow, mImeWindow);
+        assertWindowHigher(mImeWindow, imeAppTarget);
+        assertWindowHigher(mImeWindow, appBelowImeTarget);
+        assertWindowHigher(appAboveImeTarget, mImeWindow);
+        assertWindowHigher(mImeWindow, mChildAppWindowAbove);
+        assertWindowHigher(mImeWindow, mAppWindow);
+        assertWindowHigher(mNavBarWindow, mImeWindow);
+        assertWindowHigher(mStatusBarWindow, mImeWindow);
 
         // And, IME dialogs should always have an higher layer than the IME.
-        assertWindowLayerGreaterThan(mTransaction, mImeDialogWindow, mImeWindow);
+        assertWindowHigher(mImeDialogWindow, mImeWindow);
     }
 
     @Test
@@ -276,20 +279,20 @@ public class ZOrderingTests extends WindowTestsBase {
 
         // The IME target base layer is higher than all window except for the nav bar window, so the
         // IME should be above all windows except for the nav bar.
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, imeSystemOverlayTarget);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mChildAppWindowAbove);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mAppWindow);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mDockedDividerWindow);
+        assertWindowHigher(mImeWindow, imeSystemOverlayTarget);
+        assertWindowHigher(mImeWindow, mChildAppWindowAbove);
+        assertWindowHigher(mImeWindow, mAppWindow);
+        assertWindowHigher(mImeWindow, mDockedDividerWindow);
 
         // The IME has a higher base layer than the status bar so we may expect it to go
         // above the status bar once they are both in the Non-App layer, as past versions of this
         // test enforced. However this seems like the wrong behavior unless the status bar is the
         // IME target.
-        assertWindowLayerGreaterThan(mTransaction, mNavBarWindow, mImeWindow);
-        assertWindowLayerGreaterThan(mTransaction, mStatusBarWindow, mImeWindow);
+        assertWindowHigher(mNavBarWindow, mImeWindow);
+        assertWindowHigher(mStatusBarWindow, mImeWindow);
 
         // And, IME dialogs should always have an higher layer than the IME.
-        assertWindowLayerGreaterThan(mTransaction, mImeDialogWindow, mImeWindow);
+        assertWindowHigher(mImeDialogWindow, mImeWindow);
     }
 
     @Test
@@ -297,17 +300,18 @@ public class ZOrderingTests extends WindowTestsBase {
         sWm.mInputMethodTarget = mStatusBarWindow;
         mDisplayContent.assignChildLayers(mTransaction);
 
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mChildAppWindowAbove);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mAppWindow);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mDockedDividerWindow);
-        assertWindowLayerGreaterThan(mTransaction, mImeWindow, mStatusBarWindow);
+        assertWindowHigher(mImeWindow, mChildAppWindowAbove);
+        assertWindowHigher(mImeWindow, mAppWindow);
+        assertWindowHigher(mImeWindow, mDockedDividerWindow);
+        assertWindowHigher(mImeWindow, mStatusBarWindow);
 
         // And, IME dialogs should always have an higher layer than the IME.
-        assertWindowLayerGreaterThan(mTransaction, mImeDialogWindow, mImeWindow);
+        assertWindowHigher(mImeDialogWindow, mImeWindow);
     }
 
     @Test
     public void testStackLayers() throws Exception {
+        final WindowState anyWindow1 = createWindow("anyWindow");
         final WindowState pinnedStackWindow = createWindowOnStack(null, WINDOWING_MODE_PINNED,
                 ACTIVITY_TYPE_STANDARD, TYPE_BASE_APPLICATION, mDisplayContent,
                 "pinnedStackWindow");
@@ -317,12 +321,22 @@ public class ZOrderingTests extends WindowTestsBase {
         final WindowState assistantStackWindow = createWindowOnStack(null, WINDOWING_MODE_FULLSCREEN,
                 ACTIVITY_TYPE_ASSISTANT, TYPE_BASE_APPLICATION,
                 mDisplayContent, "assistantStackWindow");
+        final WindowState homeActivityWindow = createWindowOnStack(null, WINDOWING_MODE_FULLSCREEN,
+                ACTIVITY_TYPE_HOME, TYPE_BASE_APPLICATION,
+                mDisplayContent, "homeActivityWindow");
+        final WindowState anyWindow2 = createWindow("anyWindow2");
 
         mDisplayContent.assignChildLayers(mTransaction);
 
-        assertWindowLayerGreaterThan(mTransaction, dockedStackWindow, mAppWindow);
-        assertWindowLayerGreaterThan(mTransaction, assistantStackWindow, dockedStackWindow);
-        assertWindowLayerGreaterThan(mTransaction, pinnedStackWindow, assistantStackWindow);
+        assertWindowHigher(dockedStackWindow, homeActivityWindow);
+        assertWindowHigher(assistantStackWindow, homeActivityWindow);
+        assertWindowHigher(pinnedStackWindow, homeActivityWindow);
+        assertWindowHigher(anyWindow1, homeActivityWindow);
+        assertWindowHigher(anyWindow2, homeActivityWindow);
+        assertWindowHigher(pinnedStackWindow, anyWindow1);
+        assertWindowHigher(pinnedStackWindow, anyWindow2);
+        assertWindowHigher(pinnedStackWindow, dockedStackWindow);
+        assertWindowHigher(pinnedStackWindow, assistantStackWindow);
     }
 
     @Test
@@ -337,9 +351,9 @@ public class ZOrderingTests extends WindowTestsBase {
 
         // Ime should be above all app windows and below system windows if it is targeting an app
         // window.
-        assertWindowLayerGreaterThan(mTransaction, navBarPanel, mNavBarWindow);
-        assertWindowLayerGreaterThan(mTransaction, statusBarPanel, mStatusBarWindow);
-        assertWindowLayerGreaterThan(mTransaction, statusBarSubPanel, statusBarPanel);
+        assertWindowHigher(navBarPanel, mNavBarWindow);
+        assertWindowHigher(statusBarPanel, mStatusBarWindow);
+        assertWindowHigher(statusBarSubPanel, statusBarPanel);
     }
 
     @Test
@@ -347,8 +361,7 @@ public class ZOrderingTests extends WindowTestsBase {
         // TODO(b/70040778): We should aim to eliminate the last user of TYPE_APPLICATION_MEDIA
         // then we can drop all negative layering on the windowing side.
 
-        final WindowState anyWindow =
-                createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, "anyWindow");
+        final WindowState anyWindow = createWindow("anyWindow");
         final WindowState child = createWindow(anyWindow, TYPE_APPLICATION_MEDIA, mDisplayContent,
                 "TypeApplicationMediaChild");
         final WindowState mediaOverlayChild = createWindow(anyWindow, TYPE_APPLICATION_MEDIA_OVERLAY,
@@ -356,7 +369,29 @@ public class ZOrderingTests extends WindowTestsBase {
 
         mDisplayContent.assignChildLayers(mTransaction);
 
-        assertWindowLayerGreaterThan(mTransaction, anyWindow, mediaOverlayChild);
-        assertWindowLayerGreaterThan(mTransaction, mediaOverlayChild, child);
+        assertWindowHigher(anyWindow, mediaOverlayChild);
+        assertWindowHigher(mediaOverlayChild, child);
+    }
+
+    @Test
+    public void testDockedDividerPosition() throws Exception {
+        final WindowState pinnedStackWindow = createWindowOnStack(null, WINDOWING_MODE_PINNED,
+                ACTIVITY_TYPE_STANDARD, TYPE_BASE_APPLICATION, mDisplayContent,
+                "pinnedStackWindow");
+        final WindowState splitScreenWindow = createWindowOnStack(null,
+                WINDOWING_MODE_SPLIT_SCREEN_PRIMARY, ACTIVITY_TYPE_STANDARD, TYPE_BASE_APPLICATION,
+                mDisplayContent, "splitScreenWindow");
+        final WindowState splitScreenSecondaryWindow = createWindowOnStack(null,
+                WINDOWING_MODE_SPLIT_SCREEN_SECONDARY, ACTIVITY_TYPE_STANDARD,
+                TYPE_BASE_APPLICATION, mDisplayContent, "splitScreenSecondaryWindow");
+        final WindowState assistantStackWindow = createWindowOnStack(null, WINDOWING_MODE_FULLSCREEN,
+                ACTIVITY_TYPE_ASSISTANT, TYPE_BASE_APPLICATION,
+                mDisplayContent, "assistantStackWindow");
+
+        mDisplayContent.assignChildLayers(mTransaction);
+
+        assertWindowHigher(mDockedDividerWindow, splitScreenWindow);
+        assertWindowHigher(mDockedDividerWindow, splitScreenSecondaryWindow);
+        assertWindowHigher(pinnedStackWindow, mDockedDividerWindow);
     }
 }