Don't add offscreen layer twice to proto.

Fixes: 147691800
Test: Only one offscreen layer per id in dump
Change-Id: I9c741e87531ec0ed166dd1cdafc0961e243d1c96
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 0cf2f2d..16e206f 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -4290,13 +4290,8 @@
         rootProto->add_children(offscreenLayer->sequence);
 
         // Add layer
-        LayerProto* layerProto = layersProto.add_layers();
-        offscreenLayer->writeToProtoDrawingState(layerProto, traceFlags);
-        offscreenLayer->writeToProtoCommonState(layerProto, LayerVector::StateSet::Drawing,
-                                                traceFlags);
+        LayerProto* layerProto = offscreenLayer->writeToProto(layersProto, traceFlags);
         layerProto->set_parent(offscreenRootLayerId);
-
-        offscreenLayer->writeToProto(layersProto, traceFlags);
     }
 }