diff --git a/services/surfaceflinger/tests/Credentials_test.cpp b/services/surfaceflinger/tests/Credentials_test.cpp
index fa3f0e7..d33bc10 100644
--- a/services/surfaceflinger/tests/Credentials_test.cpp
+++ b/services/surfaceflinger/tests/Credentials_test.cpp
@@ -93,7 +93,7 @@
         ASSERT_TRUE(mBGSurfaceControl->isValid());
 
         Transaction t;
-        t.setDisplayLayerStack(mDisplay, 0);
+        t.setDisplayLayerStack(mDisplay, ui::DEFAULT_LAYER_STACK);
         ASSERT_EQ(NO_ERROR,
                   t.setLayer(mBGSurfaceControl, INT_MAX - 3).show(mBGSurfaceControl).apply());
     }
diff --git a/services/surfaceflinger/tests/EffectLayer_test.cpp b/services/surfaceflinger/tests/EffectLayer_test.cpp
index af00ec7..1361ded 100644
--- a/services/surfaceflinger/tests/EffectLayer_test.cpp
+++ b/services/surfaceflinger/tests/EffectLayer_test.cpp
@@ -33,7 +33,7 @@
 
         mParentLayer = createColorLayer("Parent layer", Color::RED);
         asTransaction([&](Transaction& t) {
-            t.setDisplayLayerStack(display, 0);
+            t.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
             t.setLayer(mParentLayer, INT32_MAX - 2).show(mParentLayer);
             t.setFlags(mParentLayer, layer_state_t::eLayerOpaque, layer_state_t::eLayerOpaque);
         });
diff --git a/services/surfaceflinger/tests/IPC_test.cpp b/services/surfaceflinger/tests/IPC_test.cpp
index 9fa3d4c..8d7e175 100644
--- a/services/surfaceflinger/tests/IPC_test.cpp
+++ b/services/surfaceflinger/tests/IPC_test.cpp
@@ -159,7 +159,7 @@
                                                  {0, 0, static_cast<int32_t>(width),
                                                   static_cast<int32_t>(height)},
                                                  Color::RED);
-        transaction->setLayerStack(mSurfaceControl, 0)
+        transaction->setLayerStack(mSurfaceControl, ui::DEFAULT_LAYER_STACK)
                 .setLayer(mSurfaceControl, std::numeric_limits<int32_t>::max())
                 .setBuffer(mSurfaceControl, gb)
                 .setAcquireFence(mSurfaceControl, fence)
@@ -232,7 +232,7 @@
         mDisplayHeight = mode.resolution.getHeight();
 
         Transaction setupTransaction;
-        setupTransaction.setDisplayLayerStack(mPrimaryDisplay, 0);
+        setupTransaction.setDisplayLayerStack(mPrimaryDisplay, ui::DEFAULT_LAYER_STACK);
         setupTransaction.apply();
     }
 
@@ -310,7 +310,7 @@
                                              Color::RED);
 
     Transaction transaction;
-    transaction.setLayerStack(sc, 0)
+    transaction.setLayerStack(sc, ui::DEFAULT_LAYER_STACK)
             .setLayer(sc, std::numeric_limits<int32_t>::max() - 1)
             .setBuffer(sc, gb)
             .setAcquireFence(sc, fence)
diff --git a/services/surfaceflinger/tests/LayerTransactionTest.h b/services/surfaceflinger/tests/LayerTransactionTest.h
index 0bc8fe7..6bd7920 100644
--- a/services/surfaceflinger/tests/LayerTransactionTest.h
+++ b/services/surfaceflinger/tests/LayerTransactionTest.h
@@ -266,7 +266,7 @@
     sp<IBinder> mDisplay;
     uint32_t mDisplayWidth;
     uint32_t mDisplayHeight;
-    uint32_t mDisplayLayerStack;
+    ui::LayerStack mDisplayLayerStack = ui::DEFAULT_LAYER_STACK;
     Rect mDisplayRect = Rect::INVALID_RECT;
 
     // leave room for ~256 layers
@@ -294,8 +294,6 @@
         // vsyncs.
         mBufferPostDelay = static_cast<int32_t>(1e6 / mode.refreshRate) * 3;
 
-        mDisplayLayerStack = 0;
-
         mBlackBgSurface =
                 createSurface(mClient, "BaseSurface", 0 /* buffer width */, 0 /* buffer height */,
                               PIXEL_FORMAT_RGBA_8888, ISurfaceComposerClient::eFXSurfaceEffect);
diff --git a/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp b/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp
index 43d957c..4076253 100644
--- a/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp
+++ b/services/surfaceflinger/tests/LayerTypeAndRenderTypeTransaction_test.cpp
@@ -643,7 +643,8 @@
     ASSERT_NO_FATAL_FAILURE(layer = createLayer("test", 32, 32));
     ASSERT_NO_FATAL_FAILURE(fillLayerColor(layer, Color::RED, 32, 32));
 
-    Transaction().setLayerStack(layer, mDisplayLayerStack + 1).apply();
+    const auto layerStack = ui::LayerStack::fromValue(mDisplayLayerStack.id + 1);
+    Transaction().setLayerStack(layer, layerStack).apply();
     {
         SCOPED_TRACE("non-existing layer stack");
         getScreenCapture()->expectColor(mDisplayRect, Color::BLACK);
diff --git a/services/surfaceflinger/tests/LayerUpdate_test.cpp b/services/surfaceflinger/tests/LayerUpdate_test.cpp
index ee4d367..e1a7ecc 100644
--- a/services/surfaceflinger/tests/LayerUpdate_test.cpp
+++ b/services/surfaceflinger/tests/LayerUpdate_test.cpp
@@ -63,7 +63,7 @@
         TransactionUtils::fillSurfaceRGBA8(mSyncSurfaceControl, 31, 31, 31);
 
         asTransaction([&](Transaction& t) {
-            t.setDisplayLayerStack(display, 0);
+            t.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
             t.setLayer(mBGSurfaceControl, INT32_MAX - 2).show(mBGSurfaceControl);
 
diff --git a/services/surfaceflinger/tests/MirrorLayer_test.cpp b/services/surfaceflinger/tests/MirrorLayer_test.cpp
index d027865..3ec6da9 100644
--- a/services/surfaceflinger/tests/MirrorLayer_test.cpp
+++ b/services/surfaceflinger/tests/MirrorLayer_test.cpp
@@ -36,7 +36,7 @@
         mParentLayer = createColorLayer("Parent layer", Color::RED);
         mChildLayer = createColorLayer("Child layer", Color::GREEN, mParentLayer.get());
         asTransaction([&](Transaction& t) {
-            t.setDisplayLayerStack(display, 0);
+            t.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
             t.setLayer(mParentLayer, INT32_MAX - 2).show(mParentLayer);
             t.setCrop(mChildLayer, Rect(0, 0, 400, 400)).show(mChildLayer);
             t.setPosition(mChildLayer, 50, 50);
diff --git a/services/surfaceflinger/tests/MultiDisplayLayerBounds_test.cpp b/services/surfaceflinger/tests/MultiDisplayLayerBounds_test.cpp
index 08de01c..1ed6c65 100644
--- a/services/surfaceflinger/tests/MultiDisplayLayerBounds_test.cpp
+++ b/services/surfaceflinger/tests/MultiDisplayLayerBounds_test.cpp
@@ -52,7 +52,7 @@
         mColorLayer = 0;
     }
 
-    void createDisplay(const ui::Size& layerStackSize, uint32_t layerStack) {
+    void createDisplay(const ui::Size& layerStackSize, ui::LayerStack layerStack) {
         mVirtualDisplay =
                 SurfaceComposerClient::createDisplay(String8("VirtualDisplay"), false /*secure*/);
         asTransaction([&](Transaction& t) {
@@ -63,7 +63,7 @@
         });
     }
 
-    void createColorLayer(uint32_t layerStack) {
+    void createColorLayer(ui::LayerStack layerStack) {
         mColorLayer =
                 createSurface(mClient, "ColorLayer", 0 /* buffer width */, 0 /* buffer height */,
                               PIXEL_FORMAT_RGBA_8888, ISurfaceComposerClient::eFXSurfaceEffect);
@@ -90,8 +90,9 @@
 };
 
 TEST_F(MultiDisplayLayerBoundsTest, RenderLayerInVirtualDisplay) {
-    createDisplay(mMainDisplayState.layerStackSpaceRect, 1 /* layerStack */);
-    createColorLayer(1 /* layerStack */);
+    constexpr ui::LayerStack kLayerStack{1u};
+    createDisplay(mMainDisplayState.layerStackSpaceRect, kLayerStack);
+    createColorLayer(kLayerStack);
 
     asTransaction([&](Transaction& t) { t.setPosition(mColorLayer, 10, 10); });
 
@@ -113,8 +114,8 @@
 
     // Assumption here is that the new mirrored display has the same layer stack rect as the
     // primary display that it is mirroring.
-    createDisplay(mMainDisplayState.layerStackSpaceRect, 0 /* layerStack */);
-    createColorLayer(0 /* layerStack */);
+    createDisplay(mMainDisplayState.layerStackSpaceRect, ui::DEFAULT_LAYER_STACK);
+    createColorLayer(ui::DEFAULT_LAYER_STACK);
 
     asTransaction([&](Transaction& t) { t.setPosition(mColorLayer, 10, 10); });
 
diff --git a/services/surfaceflinger/tests/RelativeZ_test.cpp b/services/surfaceflinger/tests/RelativeZ_test.cpp
index fde6e6e..50a4092 100644
--- a/services/surfaceflinger/tests/RelativeZ_test.cpp
+++ b/services/surfaceflinger/tests/RelativeZ_test.cpp
@@ -43,7 +43,7 @@
         mForegroundLayer = createColorLayer("Foreground layer", Color::GREEN);
 
         asTransaction([&](Transaction& t) {
-            t.setDisplayLayerStack(display, 0);
+            t.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
             t.setLayer(mBackgroundLayer, INT32_MAX - 2).show(mBackgroundLayer);
             t.setLayer(mForegroundLayer, INT32_MAX - 1).show(mForegroundLayer);
         });
diff --git a/services/surfaceflinger/tests/ScreenCapture_test.cpp b/services/surfaceflinger/tests/ScreenCapture_test.cpp
index ab2064e..95301b3 100644
--- a/services/surfaceflinger/tests/ScreenCapture_test.cpp
+++ b/services/surfaceflinger/tests/ScreenCapture_test.cpp
@@ -53,7 +53,7 @@
         TransactionUtils::fillSurfaceRGBA8(mFGSurfaceControl, 195, 63, 63);
 
         asTransaction([&](Transaction& t) {
-            t.setDisplayLayerStack(display, 0);
+            t.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
             t.setLayer(mBGSurfaceControl, INT32_MAX - 2).show(mBGSurfaceControl);
 
@@ -563,7 +563,7 @@
     Transaction()
             .show(redLayer)
             .show(secureLayer)
-            .setLayerStack(redLayer, 0)
+            .setLayerStack(redLayer, ui::DEFAULT_LAYER_STACK)
             .setLayer(redLayer, INT32_MAX)
             .apply();
 
@@ -655,7 +655,7 @@
     Transaction()
             .show(layer)
             .hide(mFGSurfaceControl)
-            .setLayerStack(layer, 0)
+            .setLayerStack(layer, ui::DEFAULT_LAYER_STACK)
             .setLayer(layer, INT32_MAX)
             .setColor(layer, {layerColor.r / 255, layerColor.g / 255, layerColor.b / 255})
             .setCrop(layer, bounds)
@@ -702,7 +702,7 @@
             .show(layer)
             .show(childLayer)
             .hide(mFGSurfaceControl)
-            .setLayerStack(layer, 0)
+            .setLayerStack(layer, ui::DEFAULT_LAYER_STACK)
             .setLayer(layer, INT32_MAX)
             .setColor(layer, {layerColor.r / 255, layerColor.g / 255, layerColor.b / 255})
             .setColor(childLayer, {childColor.r / 255, childColor.g / 255, childColor.b / 255})
diff --git a/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp b/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
index a424059..ee16f40 100644
--- a/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
+++ b/services/surfaceflinger/tests/SurfaceInterceptor_test.cpp
@@ -283,7 +283,7 @@
     ASSERT_TRUE(mFGSurfaceControl->isValid());
 
     Transaction t;
-    t.setDisplayLayerStack(display, 0);
+    t.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
     ASSERT_EQ(NO_ERROR,
               t.setLayer(mBGSurfaceControl, INT_MAX - 3)
                       .show(mBGSurfaceControl)
@@ -380,7 +380,7 @@
 }
 
 void SurfaceInterceptorTest::layerStackUpdate(Transaction& t) {
-    t.setLayerStack(mBGSurfaceControl, STACK_UPDATE);
+    t.setLayerStack(mBGSurfaceControl, ui::LayerStack::fromValue(STACK_UPDATE));
 }
 
 void SurfaceInterceptorTest::hiddenFlagUpdate(Transaction& t) {
diff --git a/services/surfaceflinger/tests/TransactionTestHarnesses.h b/services/surfaceflinger/tests/TransactionTestHarnesses.h
index 89f6086..60cffb1 100644
--- a/services/surfaceflinger/tests/TransactionTestHarnesses.h
+++ b/services/surfaceflinger/tests/TransactionTestHarnesses.h
@@ -65,7 +65,7 @@
 
                 SurfaceComposerClient::Transaction t;
                 t.setDisplaySurface(vDisplay, producer);
-                t.setDisplayLayerStack(vDisplay, 0);
+                t.setDisplayLayerStack(vDisplay, ui::DEFAULT_LAYER_STACK);
                 t.setDisplayProjection(vDisplay, displayState.orientation,
                                        Rect(displayState.layerStackSpaceRect), Rect(resolution));
                 t.apply();
diff --git a/services/surfaceflinger/tests/WindowInfosListener_test.cpp b/services/surfaceflinger/tests/WindowInfosListener_test.cpp
index 89228d5..de116f2 100644
--- a/services/surfaceflinger/tests/WindowInfosListener_test.cpp
+++ b/services/surfaceflinger/tests/WindowInfosListener_test.cpp
@@ -84,7 +84,7 @@
                                    ISurfaceComposerClient::eFXSurfaceBufferState);
 
     Transaction()
-            .setLayerStack(surfaceControl, 0)
+            .setLayerStack(surfaceControl, ui::DEFAULT_LAYER_STACK)
             .show(surfaceControl)
             .setLayer(surfaceControl, INT32_MAX - 1)
             .setInputWindowInfo(surfaceControl, windowInfo)
@@ -112,7 +112,7 @@
                                    ISurfaceComposerClient::eFXSurfaceBufferState);
 
     Transaction()
-            .setLayerStack(surfaceControl, 0)
+            .setLayerStack(surfaceControl, ui::DEFAULT_LAYER_STACK)
             .show(surfaceControl)
             .setLayer(surfaceControl, INT32_MAX - 1)
             .setInputWindowInfo(surfaceControl, windowInfo)
diff --git a/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
index a9e935d..b3b4ec1 100644
--- a/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
+++ b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
@@ -363,7 +363,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -426,7 +426,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -479,7 +479,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -534,7 +534,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -586,7 +586,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -651,7 +651,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -703,7 +703,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -750,7 +750,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -797,7 +797,7 @@
 
             {
                 TransactionScope ts(*mFakeComposerClient);
-                ts.setDisplayLayerStack(display, 0);
+                ts.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
                 ts.setLayer(surfaceControl, INT32_MAX - 2).show(surfaceControl);
             }
@@ -1195,7 +1195,7 @@
         fillSurfaceRGBA8(mFGSurfaceControl, RED);
 
         Transaction t;
-        t.setDisplayLayerStack(display, 0);
+        t.setDisplayLayerStack(display, ui::DEFAULT_LAYER_STACK);
 
         t.setLayer(mBGSurfaceControl, INT32_MAX - 2);
         t.show(mBGSurfaceControl);
@@ -1342,7 +1342,7 @@
         ALOGD("TransactionTest::SetLayerStack");
         {
             TransactionScope ts(*sFakeComposer);
-            ts.setLayerStack(mFGSurfaceControl, 1);
+            ts.setLayerStack(mFGSurfaceControl, ui::LayerStack{1});
         }
 
         // Foreground layer should have disappeared.
diff --git a/services/surfaceflinger/tests/unittests/CompositionTest.cpp b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
index 98c1889..0253c4c 100644
--- a/services/surfaceflinger/tests/unittests/CompositionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
@@ -82,7 +82,7 @@
 constexpr int DEFAULT_DISPLAY_HEIGHT = 1024;
 
 constexpr int DEFAULT_TEXTURE_ID = 6000;
-constexpr int DEFAULT_LAYER_STACK = 7000;
+constexpr ui::LayerStack LAYER_STACK{7000u};
 
 constexpr int DEFAULT_DISPLAY_MAX_LUMINANCE = 500;
 
@@ -287,10 +287,8 @@
 
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
                                      .setId(DEFAULT_DISPLAY_ID)
-                                     .setConnectionType(ui::DisplayConnectionType::Internal)
                                      .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
                                      .setIsSecure(Derived::IS_SECURE)
-                                     .setLayerStackId(DEFAULT_LAYER_STACK)
                                      .setPowerAdvisor(&test->mPowerAdvisor)
                                      .setName(std::string("Injected display for ") +
                                               test_info->test_case_name() + "." + test_info->name())
@@ -309,7 +307,7 @@
                                  .setPowerMode(Derived::INIT_POWER_MODE)
                                  .inject();
         Mock::VerifyAndClear(test->mNativeWindow);
-        test->mDisplay->setLayerStack(DEFAULT_LAYER_STACK);
+        test->mDisplay->setLayerStack(LAYER_STACK);
     }
 
     template <typename Case>
@@ -834,7 +832,7 @@
     template <typename L>
     static void initLayerDrawingStateAndComputeBounds(CompositionTest* test, sp<L> layer) {
         auto& layerDrawingState = test->mFlinger.mutableLayerDrawingState(layer);
-        layerDrawingState.layerStack = DEFAULT_LAYER_STACK;
+        layerDrawingState.layerStack = LAYER_STACK;
         layerDrawingState.width = 100;
         layerDrawingState.height = 100;
         layerDrawingState.color = half4(LayerProperties::COLOR[0], LayerProperties::COLOR[1],
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index 60b0f53..5a21e7b 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -139,20 +139,18 @@
     EXPECT_CALL(*mNativeWindow, perform(NATIVE_WINDOW_SET_USAGE64));
     EXPECT_CALL(*mNativeWindow, perform(NATIVE_WINDOW_API_DISCONNECT)).Times(AnyNumber());
 
-    constexpr auto kConnectionType = ui::DisplayConnectionType::Internal;
-    constexpr bool kIsPrimary = true;
-
     auto compositionDisplay =
             compositionengine::impl::createDisplay(mFlinger.getCompositionEngine(),
                                                    compositionengine::DisplayCreationArgsBuilder()
                                                            .setId(DEFAULT_DISPLAY_ID)
-                                                           .setConnectionType(kConnectionType)
                                                            .setPixels({DEFAULT_DISPLAY_WIDTH,
                                                                        DEFAULT_DISPLAY_HEIGHT})
                                                            .setPowerAdvisor(&mPowerAdvisor)
                                                            .build());
 
-    auto injector = FakeDisplayDeviceInjector(mFlinger, compositionDisplay, kConnectionType,
+    constexpr bool kIsPrimary = true;
+    auto injector = FakeDisplayDeviceInjector(mFlinger, compositionDisplay,
+                                              ui::DisplayConnectionType::Internal,
                                               DEFAULT_DISPLAY_HWC_DISPLAY_ID, kIsPrimary);
 
     injector.setNativeWindow(mNativeWindow);
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h b/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h
index de058a4..0f1cc67 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h
@@ -267,11 +267,6 @@
                 .setPixels({WIDTH, HEIGHT})
                 .setPowerAdvisor(&test->mPowerAdvisor);
 
-        const auto connectionType = CONNECTION_TYPE::value;
-        if (connectionType) {
-            ceDisplayArgs.setConnectionType(*connectionType);
-        }
-
         auto compositionDisplay =
                 compositionengine::impl::createDisplay(test->mFlinger.getCompositionEngine(),
                                                        ceDisplayArgs.build());
@@ -279,7 +274,7 @@
         auto injector =
                 TestableSurfaceFlinger::FakeDisplayDeviceInjector(test->mFlinger,
                                                                   compositionDisplay,
-                                                                  connectionType,
+                                                                  CONNECTION_TYPE::value,
                                                                   HWC_DISPLAY_ID_OPT::value,
                                                                   static_cast<bool>(PRIMARY));
 
@@ -388,7 +383,6 @@
 
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
                                      .setId(DisplayVariant::DISPLAY_ID::get())
-                                     .setConnectionType(PhysicalDisplay::CONNECTION_TYPE)
                                      .setPixels({DisplayVariant::WIDTH, DisplayVariant::HEIGHT})
                                      .setIsSecure(static_cast<bool>(DisplayVariant::SECURE))
                                      .setPowerAdvisor(&test->mPowerAdvisor)
diff --git a/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp b/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp
index 313ab03..ef53aed 100644
--- a/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp
@@ -534,8 +534,8 @@
 TEST_F(HandleTransactionLockedTest, processesDisplayLayerStackChanges) {
     using Case = NonHwcVirtualDisplayCase;
 
-    constexpr uint32_t oldLayerStack = 0u;
-    constexpr uint32_t newLayerStack = 123u;
+    constexpr ui::LayerStack oldLayerStack = ui::DEFAULT_LAYER_STACK;
+    constexpr ui::LayerStack newLayerStack{123u};
 
     // --------------------------------------------------------------------
     // Preconditions
diff --git a/services/surfaceflinger/tests/unittests/SurfaceFlinger_OnInitializeDisplaysTest.cpp b/services/surfaceflinger/tests/unittests/SurfaceFlinger_OnInitializeDisplaysTest.cpp
index ef8b149..bafa910 100644
--- a/services/surfaceflinger/tests/unittests/SurfaceFlinger_OnInitializeDisplaysTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SurfaceFlinger_OnInitializeDisplaysTest.cpp
@@ -63,15 +63,11 @@
     // The primary display should have a current state
     ASSERT_TRUE(hasCurrentDisplayState(primaryDisplay.token()));
     const auto& primaryDisplayState = getCurrentDisplayState(primaryDisplay.token());
-    // The layer stack state should be set to zero
-    EXPECT_EQ(0u, primaryDisplayState.layerStack);
-    // The orientation state should be set to zero
+
+    // The primary display state should be reset
+    EXPECT_EQ(ui::DEFAULT_LAYER_STACK, primaryDisplayState.layerStack);
     EXPECT_EQ(ui::ROTATION_0, primaryDisplayState.orientation);
-
-    // The orientedDisplaySpaceRect state should be set to INVALID
     EXPECT_EQ(Rect::INVALID_RECT, primaryDisplayState.orientedDisplaySpaceRect);
-
-    // The layerStackSpaceRect state should be set to INVALID
     EXPECT_EQ(Rect::INVALID_RECT, primaryDisplayState.layerStackSpaceRect);
 
     // The width and height should both be zero
@@ -99,4 +95,4 @@
 }
 
 } // namespace
-} // namespace android
\ No newline at end of file
+} // namespace android
diff --git a/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetDisplayStateTest.cpp b/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetDisplayStateTest.cpp
index fc40818..7d9e22b 100644
--- a/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetDisplayStateTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetDisplayStateTest.cpp
@@ -25,6 +25,8 @@
 namespace android {
 namespace {
 
+constexpr ui::LayerStack LAYER_STACK{456u};
+
 class SetDisplayStateLockedTest : public DisplayTransactionTest {};
 
 TEST_F(SetDisplayStateLockedTest, setDisplayStateLockedDoesNothingWithUnknownDisplay) {
@@ -38,7 +40,7 @@
     DisplayState state;
     state.what = DisplayState::eLayerStackChanged;
     state.token = displayToken;
-    state.layerStack = 456;
+    state.layerStack = LAYER_STACK;
 
     // --------------------------------------------------------------------
     // Invocation
@@ -167,13 +169,13 @@
     display.inject();
 
     // The display has a layer stack set
-    display.mutableCurrentDisplayState().layerStack = 456u;
+    display.mutableCurrentDisplayState().layerStack = LAYER_STACK;
 
     // The incoming request sets the same layer stack
     DisplayState state;
     state.what = DisplayState::eLayerStackChanged;
     state.token = display.token();
-    state.layerStack = 456u;
+    state.layerStack = LAYER_STACK;
 
     // --------------------------------------------------------------------
     // Invocation
@@ -187,7 +189,7 @@
     EXPECT_EQ(0u, flags);
 
     // The current display state is unchanged
-    EXPECT_EQ(456u, display.getCurrentDisplayState().layerStack);
+    EXPECT_EQ(LAYER_STACK, display.getCurrentDisplayState().layerStack);
 }
 
 TEST_F(SetDisplayStateLockedTest, setDisplayStateLockedRequestsUpdateIfLayerStackChanged) {
@@ -201,13 +203,13 @@
     display.inject();
 
     // The display has a layer stack set
-    display.mutableCurrentDisplayState().layerStack = 654u;
+    display.mutableCurrentDisplayState().layerStack = ui::LayerStack{LAYER_STACK.id + 1};
 
     // The incoming request sets a different layer stack
     DisplayState state;
     state.what = DisplayState::eLayerStackChanged;
     state.token = display.token();
-    state.layerStack = 456u;
+    state.layerStack = LAYER_STACK;
 
     // --------------------------------------------------------------------
     // Invocation
@@ -221,7 +223,7 @@
     EXPECT_EQ(eDisplayTransactionNeeded, flags);
 
     // The desired display state has been set to the new value.
-    EXPECT_EQ(456u, display.getCurrentDisplayState().layerStack);
+    EXPECT_EQ(LAYER_STACK, display.getCurrentDisplayState().layerStack);
 }
 
 TEST_F(SetDisplayStateLockedTest, setDisplayStateLockedDoesNothingIfFlagsNotChanged) {