SF: Register layers on first strong reference

In ag/9549429, LayerHistory stores a wp<Layer> on Layer construction, at
which point RefBase::mStrong is not yet 1. Since wp<T>::promote succeeds
in that case, LayerHistory may concurrently create a sp<Layer> with sole
ownership on the main thread while checking for expired weak references,
resulting in premature layer destruction.

Bug: 144218964
Test: None (sporadic crash)
Change-Id: Ia7c89a090920588b216b719fce36c9f64a126e81
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 96c17a1..a908780 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -5508,7 +5508,7 @@
     return nullptr;
 }
 
-void SurfaceFlinger::onLayerCreated(Layer* layer) {
+void SurfaceFlinger::onLayerFirstRef(Layer* layer) {
     mNumLayers++;
     mScheduler->registerLayer(layer);
 }