SF: Pass map by const reference instead of copy

Test: TreeHugger
Bug: 200284593
Change-Id: I8564cb46066c7bcd004ec2cc621a4f7e2134d34b
diff --git a/services/surfaceflinger/Tracing/TransactionProtoParser.cpp b/services/surfaceflinger/Tracing/TransactionProtoParser.cpp
index 783b36e..cf67e2a 100644
--- a/services/surfaceflinger/Tracing/TransactionProtoParser.cpp
+++ b/services/surfaceflinger/Tracing/TransactionProtoParser.cpp
@@ -43,7 +43,7 @@
 }
 
 proto::TransactionState TransactionProtoParser::toProto(
-        const std::map<int32_t /* layerId */, TracingLayerState> states) {
+        const std::map<int32_t /* layerId */, TracingLayerState>& states) {
     proto::TransactionState proto;
     for (auto& [layerId, state] : states) {
         proto::LayerState layerProto = toProto(state, nullptr);