CE: Make TimeStats nullable

This CL allows CE instances without TimeStats. This will be used by the
short lived CE instances created in the upcoming renderScreenImpl
refactor.

Bug: 238643986
Test: presubmits
Change-Id: I7f996f3ce660b335f6228069aa04bba617806b68
diff --git a/services/surfaceflinger/CompositionEngine/tests/CompositionEngineTest.cpp b/services/surfaceflinger/CompositionEngine/tests/CompositionEngineTest.cpp
index 8d99f89..60ed660 100644
--- a/services/surfaceflinger/CompositionEngine/tests/CompositionEngineTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/CompositionEngineTest.cpp
@@ -71,7 +71,7 @@
 TEST_F(CompositionEngineTest, canSetTimeStats) {
     mEngine.setTimeStats(mTimeStats);
 
-    EXPECT_EQ(mTimeStats.get(), &mEngine.getTimeStats());
+    EXPECT_EQ(mTimeStats.get(), mEngine.getTimeStats());
 }
 
 /*