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

src/profile-generator.h

Index: src/profile-generator.h
diff --git a/src/profile-generator.h b/src/profile-generator.h
index 99aeb1f5c7f167bc6e96f52228a6b5fdd201851e..f93bea600db7f6ad36f9a035e89d5688ee00aba1 100644
--- a/src/profile-generator.h
+++ b/src/profile-generator.h
@@ -30,6 +30,7 @@
 
 #include "allocation.h"
 #include "hashmap.h"
+#include "time/time.h"
 #include "../include/v8-profiler.h"
 
 namespace v8 {
@@ -216,8 +217,8 @@ class CpuProfile {
   int samples_count() const { return samples_.length(); }
   ProfileNode* sample(int index) const { return samples_.at(index); }
 
-  int64_t start_time_us() const { return start_time_us_; }
-  int64_t end_time_us() const { return end_time_us_; }
+  Time start_time() const { return start_time_; }
+  Time end_time() const { return end_time_; }
 
   void UpdateTicksScale();
 
@@ -228,8 +229,9 @@ class CpuProfile {
   const char* title_;
   unsigned uid_;
   bool record_samples_;
-  int64_t start_time_us_;
-  int64_t end_time_us_;
+  Time start_time_;
+  Time end_time_;
+  ElapsedTimer timer_;
   List<ProfileNode*> samples_;
   ProfileTree top_down_;