Updates incremental marking pass to collect object statistics.

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 89ca782c267b317fc64bcb27f4c9442bb6424a7d..ad9600bfea5e6445dfe3b85839339ecd6071f8f7 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -1297,7 +1297,7 @@ void MarkCompactMarkingVisitor::Initialize() {
   table_.Register(kVisitJSRegExp, &VisitRegExpAndFlushCode);
 
   if (FLAG_track_gc_object_stats) {
-    ObjectStatsVisitor::Initialize(&table_);
+    MarkCompactObjectStatsVisitor::Initialize(&table_);
   }
 }
 
@@ -2208,6 +2208,10 @@ void MarkCompactCollector::MarkLiveObjects() {
     } else {
       // Abort any pending incremental activities e.g. incremental sweeping.
       incremental_marking->Stop();
+      if (FLAG_track_gc_object_stats) {

[Hannes Payer (out of office), 2016/05/11 15:43:56]

I think it is cleaner to clear the object stats right after printing the trace
information.

[mythria, 2016/05/11 15:52:26]

They are already cleared after printing trace information (at the end of this
function). I thought we may have to clear here as well to avoid counting the
objects twice. I thought since we are aborting incremental marking the object
stats collected during incremental marking should be cleared. If it is just
sufficient to clear after printing trace information, I will just remove it.

+        // Clear object stats collected during incremental marking.
+        heap()->object_stats_->ClearObjectStats();
+      }
       if (marking_deque_.in_use()) {
         marking_deque_.Uninitialize(true);
       }