Use TracedValue in runtime statistics.

src/counters.h

Index: src/counters.h
diff --git a/src/counters.h b/src/counters.h
index 495a023ebee2699ce47bf0a5190989e6e1d72c28..96102963dd4c6bce5d9e99452a054ae48a082b0e 100644
--- a/src/counters.h
+++ b/src/counters.h
@@ -15,6 +15,7 @@
 #include "src/objects.h"
 #include "src/runtime/runtime.h"
 #include "src/tracing/trace-event.h"
+#include "src/tracing/traced-value.h"
 
 namespace v8 {
 namespace internal {
@@ -484,7 +485,6 @@ double AggregatedMemoryHistogram<Histogram>::Aggregate(double current_ms,
 struct RuntimeCallCounter {
   explicit RuntimeCallCounter(const char* name) : name(name) {}
   void Reset();
-  V8_NOINLINE void Dump(std::stringstream& out);
 
   const char* name;
   int64_t count = 0;
@@ -799,7 +799,7 @@ class RuntimeCallStats {
 
   void Reset();
   V8_NOINLINE void Print(std::ostream& os);
-  V8_NOINLINE std::string Dump();
+  V8_NOINLINE void Dump(v8::tracing::TracedValue* value);
 
   RuntimeCallStats() {
     Reset();
@@ -810,7 +810,6 @@ class RuntimeCallStats {
   bool InUse() { return in_use_; }
 
  private:
-  std::stringstream buffer_;
   // Counter to track recursive time events.
   RuntimeCallTimer* current_timer_ = NULL;
   // Used to track nested tracing scopes.