Oilpan: Add support of pre-finalization callback to Oilpan infrastructure.

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index d3bc5cf73f62b1ae1a609758caa3d729b47f007e..2b0af09f013acf641b65558cb03cb778397ae506 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -1114,6 +1114,7 @@ void ThreadState::performPendingSweep()
             // Perform thread-specific weak processing.
             while (popAndInvokeWeakPointerCallback(Heap::s_markingVisitor)) { }
         }
+        invokePreFinalizer(*Heap::s_markingVisitor);
         leaveNoAllocationScope();
 
         // Perform sweeping and finalization.
@@ -1247,6 +1248,25 @@ ThreadState::AttachedThreadStateSet& ThreadState::attachedThreads()
     return threads;
 }
 
+void ThreadState::unregisterObjectWithPreFinalizerInternal(void* target)
+{
+    if (isSweepInProgress())
+        return;
+    auto it = m_objectsWithPreFinalizer.find(target);
+    ASSERT(it != m_objectsWithPreFinalizer.end());
+    m_objectsWithPreFinalizer.remove(it);
+}
+
+void ThreadState::invokePreFinalizer(Visitor& visitor)
+{
+    Vector<void*> deadObjects;
+    for (auto& entry : m_objectsWithPreFinalizer) {
+        if (entry.value(entry.key, visitor))
+            deadObjects.append(entry.key);
+    }
+    m_objectsWithPreFinalizer.removeAll(deadObjects);
+}
+
 #if ENABLE(GC_PROFILE_MARKING)
 const GCInfo* ThreadState::findGCInfoFromAllThreads(Address address)
 {