Add information about time spent in external callback to...

src/heap.h

Index: src/heap.h
===================================================================
--- src/heap.h	(revision 3959)
+++ src/heap.h	(working copy)
@@ -1520,8 +1520,23 @@
 
 class GCTracer BASE_EMBEDDED {
  public:
+  // Time spent while in the external scope counts towards the
+  // external time in the tracer and will be reported separately.
+  class ExternalScope BASE_EMBEDDED {
+   public:
+    explicit ExternalScope(GCTracer* tracer) : tracer_(tracer) {
+      start_time_ = OS::TimeCurrentMillis();
+    }
+    ~ExternalScope() {
+      tracer_->external_time_ += OS::TimeCurrentMillis() - start_time_;
+    }
+
+   private:
+    GCTracer* tracer_;
+    double start_time_;
+  };
+
   GCTracer();
-
   ~GCTracer();
 
   // Sets the collector.
@@ -1555,6 +1570,9 @@
   double start_size_;  // Size of objects in heap set in constructor.
   GarbageCollector collector_;  // Type of collector.
 
+  // Keep track of the amount of time spent in external callbacks.
+  double external_time_;
+
   // A count (including this one, eg, the first collection is 1) of the
   // number of garbage collections.
   int gc_count_;