SF: Define DisplayId as struct type
This prevents accidental mix-up with HWC display IDs, which have the
same backing type, as well as other implicitly convertible integers,
e.g. EDID manufacturer IDs. This CL also fixes misuses detected by
type checking:
1) Recycling of virtual display IDs.
2) Skipping composition for non-HWC virtual displays.
3) Unit tests for fallback/virtual display IDs.
Bug: 74619554
Bug: 119412688
Test: libsurfaceflinger_unittest
Test: vrflinger_test on walleye_xr
Change-Id: I0be41cc93c82860e859f1adf427430436c926595
diff --git a/services/surfaceflinger/tests/unittests/CompositionTest.cpp b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
index 09bb8c5..de6420e 100644
--- a/services/surfaceflinger/tests/unittests/CompositionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
@@ -65,7 +65,7 @@
constexpr hwc2_layer_t HWC_LAYER = 5000;
constexpr Transform DEFAULT_TRANSFORM = static_cast<Transform>(0);
-constexpr DisplayId DEFAULT_DISPLAY_ID = 42;
+constexpr DisplayId DEFAULT_DISPLAY_ID = DisplayId{42};
constexpr int DEFAULT_DISPLAY_WIDTH = 1920;
constexpr int DEFAULT_DISPLAY_HEIGHT = 1024;