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());
 }
 
 /*
diff --git a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
index a955178..2109987 100644
--- a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
@@ -3332,8 +3332,7 @@
 
         EXPECT_CALL(mOutput, getCompositionEngine()).WillRepeatedly(ReturnRef(mCompositionEngine));
         EXPECT_CALL(mCompositionEngine, getRenderEngine()).WillRepeatedly(ReturnRef(mRenderEngine));
-        EXPECT_CALL(mCompositionEngine, getTimeStats())
-                .WillRepeatedly(ReturnRef(*mTimeStats.get()));
+        EXPECT_CALL(mCompositionEngine, getTimeStats()).WillRepeatedly(Return(mTimeStats.get()));
         EXPECT_CALL(*mDisplayColorProfile, getHdrCapabilities())
                 .WillRepeatedly(ReturnRef(kHdrCapabilities));
     }