[Tracing] Embed V8 runtime call stats into tracing.

src/counters.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COUNTERS_H_
 #define V8_COUNTERS_H_
 
 #include "include/v8.h"
 #include "src/allocation.h"
 #include "src/base/platform/elapsed-timer.h"
@@ skipping 464 matching lines @@
   // The aggregate_value_ is the average for [start_ms_; last_ms_].
   // The value is the average for [last_ms_; current_ms].
   // Return the weighted average of the aggregate_value_ and the value.
   return aggregate_value_ * ((last_ms_ - start_ms_) / interval_ms) +
          value * ((current_ms - last_ms_) / interval_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;
   base::TimeDelta time;
 };
 
 // RuntimeCallTimer is used to keep track of the stack of currently active
 // timers used for properly measuring the own time of a RuntimeCallCounter.
 class RuntimeCallTimer {
  public:
@@ skipping 739 matching lines @@
 
   explicit Counters(Isolate* isolate);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(Counters);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COUNTERS_H_