Reland "Add Chromium-style TimeDelta, Time and TimeTicks classes, and a new ElapsedTimer class."

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 42 matching lines @@
 
 void* Histogram::CreateHistogram() const {
   return isolate()->stats_table()->
       CreateHistogram(name_, min_, max_, num_buckets_);
 }
 
 
 // Start the timer.
 void HistogramTimer::Start() {
   if (Enabled()) {
-    stop_time_ = 0;
-    start_time_ = OS::Ticks();
+    timer_.Start();
   }
   if (FLAG_log_internal_timer_events) {
     LOG(isolate(), TimerEvent(Logger::START, name()));
   }
 }
 
 
 // Stop the timer and record the results.
 void HistogramTimer::Stop() {
   if (Enabled()) {
-    stop_time_ = OS::Ticks();
     // Compute the delta between start and stop, in milliseconds.
-    int milliseconds = static_cast<int>(stop_time_ - start_time_) / 1000;
-    AddSample(milliseconds);
+    AddSample(static_cast<int>(timer_.Elapsed().InMilliseconds()));
+    timer_.Stop();
   }
   if (FLAG_log_internal_timer_events) {
     LOG(isolate(), TimerEvent(Logger::END, name()));
   }
 }
 
 } }  // namespace v8::internal