SF: Fix a defect in the layer filtering logic

Change 32cbe2 broke the layer filtering logic when moving it over to
CompositionEngine. It would allow certain layers to appear on a virtual
display when they were supposed to be filtered out.

This corrects the logic to be what it was supposed to be, and adds a
unit test that verifies and documents the expected behavior.

Bug: 123248930
Test: atest libsurfaceflinger_unittest libcompositionengine_test
Test: atest android.media.cts.EncodeVirtualDisplayWithCompositionTest

Change-Id: Id2c4b4d32da405c64533924027795620f2d6ee61
diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index 54111de..4a13bfb 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -166,7 +166,7 @@
 // ----------------------------------------------------------------------------
 
 void DisplayDevice::setLayerStack(uint32_t stack) {
-    mCompositionDisplay->setLayerStackFilter(!isPrimary(), stack);
+    mCompositionDisplay->setLayerStackFilter(stack, isPrimary());
 }
 
 // ----------------------------------------------------------------------------
@@ -330,7 +330,7 @@
 }
 
 uint32_t DisplayDevice::getLayerStack() const {
-    return mCompositionDisplay->getState().singleLayerStackId;
+    return mCompositionDisplay->getState().layerStackId;
 }
 
 const ui::Transform& DisplayDevice::getTransform() const {