Use enum for per thread heap enabled flag

third_party/WebKit/Source/platform/heap/Heap.cpp

 /*
  * Copyright (C) 2013 Google Inc. 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
@@ skipping 266 matching lines @@
         SafePointAwareMutexLocker locker(m_threadAttachMutex, BlinkGC::NoHeapPointersOnStack);
         thread->runTerminationGC();
         ASSERT(m_threads.contains(thread));
         m_threads.remove(thread);
         isLastThread = m_threads.isEmpty();
     }
     // The last thread begin detached should be the owning thread, which would
     // be the main thread for the mainThreadHeap and a per thread heap enabled
     // thread otherwise.
     if (isLastThread)
-        DCHECK(thread->perThreadHeapEnabled() || thread->isMainThread());
+        DCHECK(thread->threadHeapMode() == BlinkGC::PerThreadHeapMode || thread->isMainThread());
     if (thread->isMainThread())
         DCHECK_EQ(heapStats().allocatedSpace(), 0u);
     if (isLastThread)
         delete this;
 }
 
 bool ThreadHeap::park()
 {
     return m_safePointBarrier->parkOthers();
 }
@@ skipping 341 matching lines @@
     ProcessHeap::decreaseTotalMarkedObjectSize(m_stats.markedObjectSize());
 
     m_stats.reset();
     for (ThreadState* state : m_threads)
         state->resetHeapCounters();
 }
 
 ThreadHeap* ThreadHeap::s_mainThreadHeap = nullptr;
 
 } // namespace blink