Restore the bytes promoted counter.

runtime/vm/scavenger.cc

Index: runtime/vm/scavenger.cc
diff --git a/runtime/vm/scavenger.cc b/runtime/vm/scavenger.cc
index f6273457278a9649199f5d958cdc28428cca6212..0cc302c58595db68f1cad8326a61d067ea034745 100644
--- a/runtime/vm/scavenger.cc
+++ b/runtime/vm/scavenger.cc
@@ -74,6 +74,7 @@ class ScavengerVisitor : public ObjectPointerVisitor {
         vm_heap_(Dart::vm_isolate()->heap()),
         delayed_weak_stack_(),
         growth_policy_(PageSpace::kControlGrowth),
+        bytes_promoted_(0),
         visiting_old_pointers_(false),
         in_scavenge_pointer_(false) {}
 
@@ -108,6 +109,8 @@ class ScavengerVisitor : public ObjectPointerVisitor {
     }
   }
 
+  intptr_t bytes_promoted() const { return bytes_promoted_; }
+
  private:
   void UpdateStoreBuffer(RawObject** p, RawObject* obj) {
     uword ptr = reinterpret_cast<uword>(p);
@@ -184,6 +187,7 @@ class ScavengerVisitor : public ObjectPointerVisitor {
           // If promotion succeeded then we need to remember it so that it can
           // be traversed later.
           scavenger_->PushToPromotedStack(new_addr);
+          bytes_promoted_ += size;
           if (HeapTrace::is_enabled()) {
             heap_->trace()->TracePromotion(raw_addr, new_addr);
           }
@@ -196,6 +200,7 @@ class ScavengerVisitor : public ObjectPointerVisitor {
           new_addr = heap_->TryAllocate(size, Heap::kOld, growth_policy_);
           if (new_addr != 0) {
             scavenger_->PushToPromotedStack(new_addr);
+            bytes_promoted_ += size;
             if (HeapTrace::is_enabled()) {
               heap_->trace()->TracePromotion(raw_addr, new_addr);
             }
@@ -242,6 +247,9 @@ class ScavengerVisitor : public ObjectPointerVisitor {
   DelaySet delay_set_;
   GrowableArray<RawObject*> delayed_weak_stack_;
   PageSpace::GrowthPolicy growth_policy_;
+  // TODO(cshapiro): use this value to compute survival statistics for
+  // new space growth policy.
+  intptr_t bytes_promoted_;
 
   bool visiting_old_pointers_;
   bool in_scavenge_pointer_;