Oilpan: Introduce a state transition model for Oilpan GC states

Source/platform/heap/Heap.h

 /*
  * 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 900 matching lines @@
     template<typename T> static Address reallocate(void* previous, size_t);
 
     static void collectGarbage(ThreadState::StackState, ThreadState::CauseOfGC = ThreadState::NormalGC);
     static void collectGarbageForTerminatingThread(ThreadState*);
     static void collectAllGarbage();
     template<CallbackInvocationMode Mode> static void processMarkingStack();
     static void postMarkingProcessing();
     static void globalWeakProcessing();
     static void setForcePreciseGCForTesting();
 
-    static void prepareForGC();
+    static void preGC();
+    static void postGC();
 
     // Conservatively checks whether an address is a pointer in any of the thread
     // heaps. If so marks the object pointed to as live.
     static Address checkAndMarkPointer(Visitor*, Address);
 
 #if ENABLE(GC_PROFILE_MARKING)
     // Dump the path to specified object on the next GC. This method is to be invoked from GDB.
     static void dumpPathToObjectOnNextGC(void* p);
 
     // Forcibly find GCInfo of the object at Address.
@@ skipping 1412 matching lines @@
 template<typename T, size_t inlineCapacity>
 struct GCInfoTrait<HeapVector<T, inlineCapacity> > : public GCInfoTrait<Vector<T, inlineCapacity, HeapAllocator> > { };
 template<typename T, size_t inlineCapacity>
 struct GCInfoTrait<HeapDeque<T, inlineCapacity> > : public GCInfoTrait<Deque<T, inlineCapacity, HeapAllocator> > { };
 template<typename T, typename U, typename V>
 struct GCInfoTrait<HeapHashCountedSet<T, U, V> > : public GCInfoTrait<HashCountedSet<T, U, V, HeapAllocator> > { };
 
 } // namespace blink
 
 #endif // Heap_h