Use EmbedderHeapTracer instead of object grouping when trace_embedder_heap flag is set

src/heap/heap.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_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 894 matching lines @@
         return lo_space();
       default:
         return paged_space(idx);
     }
   }
 
   // Returns name of the space.
   const char* GetSpaceName(int idx);
 
   // ===========================================================================
-  // API. ======================================================================
+  // Embedder heap tracing. ====================================================
   // ===========================================================================
 
   void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
 
+  EmbedderHeapTracer* embedder_heap_tracer() { return embedder_heap_tracer_; }

[Hannes Payer (out of office), 2016/04/07 20:38:31]

Since the tracer is fully used in mark-compact, it should actually live there.

[Marcel Hlopko, 2016/04/08 08:08:09]

Done.

+
+  bool UsingEmbedderHeapTracer() { return embedder_heap_tracer_; }

[Hannes Payer (out of office), 2016/04/07 20:38:30]

Why don't we just check FLAG_trace_object_groups?

[Marcel Hlopko, 2016/04/08 08:08:10]

I removed the flag (or to be more accurrate, moved it to chromium). The embedder
heap tracing feature is now controlled only by the presence of the heap tracer.
If embedder sets it, v8 will use it. If it's nullptr, v8 will use object
grouping.

+
+  void TracePossibleWrapper(JSObject* js_object);
+
   void RegisterExternallyReferencedObject(Object** object);
 
   // ===========================================================================
   // Getters to other components. ==============================================
   // ===========================================================================
 
   GCTracer* tracer() { return tracer_; }
 
   MemoryAllocator* memory_allocator() { return memory_allocator_; }
 
-  EmbedderHeapTracer* embedder_heap_tracer() { return embedder_heap_tracer_; }
-
   PromotionQueue* promotion_queue() { return &promotion_queue_; }
 
   inline Isolate* isolate();
 
   MarkCompactCollector* mark_compact_collector() {
     return mark_compact_collector_;
   }
 
   // ===========================================================================
   // Root set access. ==========================================================
@@ skipping 1719 matching lines @@
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_