diff --git a/services/surfaceflinger/SurfaceTracing.h b/services/surfaceflinger/SurfaceTracing.h
index 590ab96..fd8cb82 100644
--- a/services/surfaceflinger/SurfaceTracing.h
+++ b/services/surfaceflinger/SurfaceTracing.h
@@ -18,7 +18,9 @@
 
 #include <layerproto/LayerProtoHeader.h>
 #include <utils/Errors.h>
+#include <utils/String8.h>
 
+#include <memory>
 #include <mutex>
 
 using namespace android::surfaceflinger;
@@ -32,9 +34,10 @@
 public:
     void enable();
     status_t disable();
-    bool isEnabled();
+    bool isEnabled() const;
 
     void traceLayers(const char* where, LayersProto);
+    void dump(String8& result) const;
 
 private:
     static constexpr auto DEFAULT_FILENAME = "/data/misc/wmtrace/layers_trace.pb";
@@ -43,8 +46,8 @@
 
     bool mEnabled = false;
     std::string mOutputFileName = DEFAULT_FILENAME;
-    std::mutex mTraceMutex;
-    LayersTraceFileProto mTrace;
+    mutable std::mutex mTraceMutex;
+    std::unique_ptr<LayersTraceFileProto> mTrace;
 };
 
 } // namespace android