When adjusting page's live bytes counter from the mutator adjust owners unswept free bytes counter.

src/mark-compact.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 180 matching lines @@
 
   void SetOverflowed() { overflowed_ = true; }
 
   // Push the (marked) object on the marking stack if there is room,
   // otherwise mark the object as overflowed and wait for a rescan of the
   // heap.
   inline void PushBlack(HeapObject* object) {
     ASSERT(object->IsHeapObject());
     if (IsFull()) {
       Marking::BlackToGrey(object);
-      MemoryChunk::IncrementLiveBytes(object->address(), -object->Size());
+      MemoryChunk::IncrementLiveBytesFromGC(object->address(), -object->Size());
       SetOverflowed();
     } else {
       array_[top_] = object;
       top_ = ((top_ + 1) & mask_);
     }
   }
 
   inline void PushGrey(HeapObject* object) {
     ASSERT(object->IsHeapObject());
     if (IsFull()) {
@@ skipping 533 matching lines @@
 
   friend class Heap;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_