v8: make GCTracer persistent.

src/incremental-marking.cc

Index: src/incremental-marking.cc
diff --git a/src/incremental-marking.cc b/src/incremental-marking.cc
index 8e2eb62357664d39f378530af1408e0f6202b9b9..4afc8bcf2123b9bbc69b93a60b0f90c2b1b50e8b 100644
--- a/src/incremental-marking.cc
+++ b/src/incremental-marking.cc
@@ -21,13 +21,8 @@ IncrementalMarking::IncrementalMarking(Heap* heap)
       state_(STOPPED),
       marking_deque_memory_(NULL),
       marking_deque_memory_committed_(false),
-      steps_count_(0),
-      steps_took_(0),
-      longest_step_(0.0),
       old_generation_space_available_at_start_of_incremental_(0),
       old_generation_space_used_at_start_of_incremental_(0),
-      steps_count_since_last_gc_(0),
-      steps_took_since_last_gc_(0),
       should_hurry_(false),
       marking_speed_(0),
       allocated_(0),
@@ -660,9 +655,7 @@ void IncrementalMarking::UpdateMarkingDequeAfterScavenge() {
   }
   marking_deque_.set_top(new_top);
 
-  steps_took_since_last_gc_ = 0;
-  steps_count_since_last_gc_ = 0;
-  longest_step_ = 0.0;
+  heap_->tracer()->reset_step_counters(false);
 }
 
 
@@ -896,12 +889,10 @@ void IncrementalMarking::Step(intptr_t allocated_bytes,
     if (marking_deque_.IsEmpty()) MarkingComplete(action);
   }
 
-  steps_count_++;
-  steps_count_since_last_gc_++;
-
   bool speed_up = false;
 
-  if ((steps_count_ % kMarkingSpeedAccellerationInterval) == 0) {
+  int steps_count = heap_->tracer()->steps_count();
+  if (((steps_count + 1) % kMarkingSpeedAccellerationInterval) == 0) {
     if (FLAG_trace_gc) {
       PrintPID("Speed up marking after %d steps\n",
                static_cast<int>(kMarkingSpeedAccellerationInterval));
@@ -966,24 +957,18 @@ void IncrementalMarking::Step(intptr_t allocated_bytes,
       FLAG_print_cumulative_gc_stat) {
     double end = base::OS::TimeCurrentMillis();
     double delta = (end - start);
-    longest_step_ = Max(longest_step_, delta);
-    steps_took_ += delta;
-    steps_took_since_last_gc_ += delta;
+    heap_->tracer()->add_step(delta);
     heap_->AddMarkingTime(delta);
   }
 }
 
 
 void IncrementalMarking::ResetStepCounters() {
-  steps_count_ = 0;
-  steps_took_ = 0;
-  longest_step_ = 0.0;
+  heap_->tracer()->reset_step_counters(true);
   old_generation_space_available_at_start_of_incremental_ =
       SpaceLeftInOldSpace();
   old_generation_space_used_at_start_of_incremental_ =
       heap_->PromotedTotalSize();
-  steps_count_since_last_gc_ = 0;
-  steps_took_since_last_gc_ = 0;
   bytes_rescanned_ = 0;
   marking_speed_ = kInitialMarkingSpeed;
   bytes_scanned_ = 0;