[counters] adding more counters and log-events

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 310 matching lines @@
   void Start() { time_ = base::TimeDelta(); }
   void Stop() { AddSample(static_cast<int>(time_.InMicroseconds())); }
 
   // Add a time value ("inner" scope).
   void Add(base::TimeDelta other) { time_ += other; }
 
  private:
   base::TimeDelta time_;
 };
 
-
-// A helper class for use with AggregatableHistogramTimer.
+// A helper class for use with AggregatableHistogramTimer. This is the
+// outer-most timer scope used with an AggregatableHistogramTimer. It will
+// aggregate the information from the inner AggregatedHistogramTimerScope.
 class AggregatingHistogramTimerScope {
  public:
   explicit AggregatingHistogramTimerScope(AggregatableHistogramTimer* histogram)
       : histogram_(histogram) {
     histogram_->Start();
   }
   ~AggregatingHistogramTimerScope() { histogram_->Stop(); }
 
  private:
   AggregatableHistogramTimer* histogram_;
 };
 
-
-// A helper class for use with AggregatableHistogramTimer.
+// A helper class for use with AggregatableHistogramTimer, the "inner" scope
+// which defines the events to be timed.
 class AggregatedHistogramTimerScope {
  public:
   explicit AggregatedHistogramTimerScope(AggregatableHistogramTimer* histogram)
       : histogram_(histogram) {
     timer_.Start();
   }
   ~AggregatedHistogramTimerScope() { histogram_->Add(timer_.Elapsed()); }
 
  private:
   base::ElapsedTimer timer_;
@@ skipping 539 matching lines @@
 
   explicit Counters(Isolate* isolate);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(Counters);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COUNTERS_H_