Add a callback for rendernode parentcount=0

Bug: 27709981
Fixes: 22565656

Change-Id: I1cb4461baf9069dc4e7ca6de10d5862578c107f4
diff --git a/libs/hwui/Android.mk b/libs/hwui/Android.mk
index 1f17851..be816f78 100644
--- a/libs/hwui/Android.mk
+++ b/libs/hwui/Android.mk
@@ -252,6 +252,7 @@
     tests/unit/LinearAllocatorTests.cpp \
     tests/unit/MatrixTests.cpp \
     tests/unit/OffscreenBufferPoolTests.cpp \
+    tests/unit/RenderNodeTests.cpp \
     tests/unit/SkiaBehaviorTests.cpp \
     tests/unit/StringUtilsTests.cpp \
     tests/unit/TextDropShadowCacheTests.cpp \