[TimeStats] Track RenderEngine time per frame.

Bug: 144037240
Test: dumpsys SurfaceFlinger --timestats -dump
Change-Id: I7a4dd680ed08e3a7a05e3fd08d5e133e9d394193
diff --git a/services/surfaceflinger/CompositionEngine/src/Output.cpp b/services/surfaceflinger/CompositionEngine/src/Output.cpp
index 6877f8b..5f752a0 100644
--- a/services/surfaceflinger/CompositionEngine/src/Output.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Output.cpp
@@ -838,9 +838,18 @@
         setExpensiveRenderingExpected(true);
     }
 
+    const nsecs_t renderEngineStart = systemTime();
     renderEngine.drawLayers(clientCompositionDisplay, clientCompositionLayers,
                             buf->getNativeBuffer(), /*useFramebufferCache=*/true, std::move(fd),
                             &readyFence);
+    auto& timeStats = getCompositionEngine().getTimeStats();
+    if (readyFence.get() < 0) {
+        timeStats.recordRenderEngineDuration(renderEngineStart, systemTime());
+    } else {
+        timeStats.recordRenderEngineDuration(renderEngineStart,
+                                             std::make_shared<FenceTime>(
+                                                     new Fence(dup(readyFence.get()))));
+    }
 
     if (expensiveRenderingExpected) {
         setExpensiveRenderingExpected(false);