Log event start and event end separately when using --log-timer-events.

src/counters.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 59 matching lines @@
   }
 }
 
 void* Histogram::CreateHistogram() const {
   return Isolate::Current()->stats_table()->
       CreateHistogram(name_, min_, max_, num_buckets_);
 }
 
 // Start the timer.
 void HistogramTimer::Start() {
-  if (histogram_.Enabled() || FLAG_log_internal_timer_events) {
+  if (histogram_.Enabled()) {
     stop_time_ = 0;
     start_time_ = OS::Ticks();
   }
+  if (FLAG_log_internal_timer_events) {
+    LOG(Isolate::Current(), TimerEvent(Logger::START, histogram_.name_));
+  }
 }
 
 // Stop the timer and record the results.
 void HistogramTimer::Stop() {
   if (histogram_.Enabled()) {
     stop_time_ = OS::Ticks();
     // Compute the delta between start and stop, in milliseconds.
     int milliseconds = static_cast<int>(stop_time_ - start_time_) / 1000;
     histogram_.AddSample(milliseconds);
   }
   if (FLAG_log_internal_timer_events) {
-    LOG(Isolate::Current(),
-        TimerEvent(histogram_.name_, start_time_, OS::Ticks()));
+    LOG(Isolate::Current(), TimerEvent(Logger::END, histogram_.name_));
   }
 }
 
 } }  // namespace v8::internal