[Tracing] Use TracingCategoryObserver in gc statistics

src/heap/heap-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
 #include "src/counters-inl.h"
 #include "src/heap/heap.h"
 #include "src/heap/incremental-marking-inl.h"
 #include "src/heap/mark-compact.h"
+#include "src/heap/object-stats.h"
 #include "src/heap/remembered-set.h"
 #include "src/heap/spaces-inl.h"
 #include "src/heap/store-buffer.h"
 #include "src/isolate.h"
 #include "src/list-inl.h"
 #include "src/log.h"
 #include "src/msan.h"
 #include "src/objects-inl.h"
 #include "src/type-feedback-vector-inl.h"
 
@@ skipping 777 matching lines @@
   int next_serial_number = next_template_serial_number()->value() + 1;
   set_next_template_serial_number(Smi::FromInt(next_serial_number));
   return next_serial_number;
 }
 
 void Heap::SetSerializedTemplates(FixedArray* templates) {
   DCHECK_EQ(empty_fixed_array(), serialized_templates());
   set_serialized_templates(templates);
 }
 
+void Heap::CreateObjectStats() {
+  if (V8_LIKELY(FLAG_gc_stats == 0)) return;
+  if (!live_object_stats_) {
+    live_object_stats_ = new ObjectStats(this);
+  }
+  if (!dead_object_stats_) {
+    dead_object_stats_ = new ObjectStats(this);
+  }
+}
+
 AlwaysAllocateScope::AlwaysAllocateScope(Isolate* isolate)
     : heap_(isolate->heap()) {
   heap_->always_allocate_scope_count_.Increment(1);
 }
 
 
 AlwaysAllocateScope::~AlwaysAllocateScope() {
   heap_->always_allocate_scope_count_.Increment(-1);
 }
 
@@ skipping 11 matching lines @@
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_INL_H_