Add more timing information in the VM to track time spent is dart code Vs native code.

runtime/vm/native_arguments.h

Index: runtime/vm/native_arguments.h
===================================================================
--- runtime/vm/native_arguments.h	(revision 32362)
+++ runtime/vm/native_arguments.h	(working copy)
@@ -221,6 +221,40 @@
   RawObject** retval_;  // Pointer to the return value area.
 };
 
+class DartToNativeTimerScope : public ValueObject {

[turnidge, 2014/02/11 21:24:33]

Two notes:

1) Did you consider putting all of these timer scope objects in timer.h?

Also...

2) 

If we had the TimerList object keep track of which Timer is currently active,
then we could just have a single TimerScope class.   Here's a cruddy
implementation for discussion:

  explicit TimerScope(Isolate* isolate, Timer* timer) : isolate_(isolate) {
    saved_timer_ = isolate->timer_list()->active_timer();
    isolate->timer_list()->activate(timer);  // deactivates current.  timer may
be NULL.
  }

  ~TimerScope() {
    isolate_->timer_list()->activate(saved_timer_);
  }

There would be the odd case that the total timer is special, etc.  I'm not
saying to do this, just asking if you've thought about it.

[siva, 2014/02/19 22:38:30]

Created a new file timer_scope.h and moved all the Scopes over to this file.
As discussed offline we have some overlapping timers and it makes one scope
object mutually excluding timers can be difficult, we could maybe as this
stabilizes move towards having one common execution timer scope which
transitions dart/native and vm execution states.

+ public:
+  explicit DartToNativeTimerScope(Isolate* isolate) {
+    dart_timer_ = &(isolate->timer_list().time_dart_execution());
+    native_timer_ = &(isolate->timer_list().time_native_execution());
+    dart_timer_->Stop();
+    native_timer_->Start();
+  }
+  ~DartToNativeTimerScope() {
+    native_timer_->Stop();
+    dart_timer_->Start();
+  }
+
+ private:
+  Timer* native_timer_;
+  Timer* dart_timer_;
+  DISALLOW_COPY_AND_ASSIGN(DartToNativeTimerScope);
+};
+
+class DartToVmTimerScope : public ValueObject {
+ public:
+  explicit DartToVmTimerScope(Isolate* isolate) {
+    dart_timer_ = &(isolate->timer_list().time_dart_execution());
+    dart_timer_->Stop();
+  }
+  ~DartToVmTimerScope() {
+    dart_timer_->Start();
+  }
+
+ private:
+  Timer* dart_timer_;
+  DISALLOW_COPY_AND_ASSIGN(DartToVmTimerScope);
+};
+
 }  // namespace dart
 
 #endif  // VM_NATIVE_ARGUMENTS_H_