Oilpan: We need to collect all garbage before shutting down the worker thread

Source/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 762 matching lines @@
     static bool popAndInvokeTraceCallback(Visitor*);
 
     // Pop the top of the weak callback stack and call the callback with the visitor
     // and the object. Returns false when there is nothing more to do.
     static bool popAndInvokeWeakPointerCallback(Visitor*);
 
     template<typename T> static Address allocate(size_t);
     template<typename T> static Address reallocate(void* previous, size_t);
 
     static void collectGarbage(ThreadState::StackState, GCType = Normal);
+    static void collectAllGarbage(ThreadState::StackState, GCType = Normal);
 
     static void prepareForGC();
 
     // 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);
 
     // Collect heap stats for all threads attached to the Blink
     // garbage collector. Should only be called during garbage
     // collection where threads are known to be at safe points.
@@ skipping 898 matching lines @@
 // to export. This forces it to export all the methods from ThreadHeap.
 template<> void ThreadHeap<FinalizedHeapObjectHeader>::addPageToHeap(const GCInfo*);
 template<> void ThreadHeap<HeapObjectHeader>::addPageToHeap(const GCInfo*);
 extern template class HEAP_EXPORT ThreadHeap<FinalizedHeapObjectHeader>;
 extern template class HEAP_EXPORT ThreadHeap<HeapObjectHeader>;
 #endif
 
 }
 
 #endif // Heap_h