Unify and generalize thread static persistent finalization.

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

Index: third_party/WebKit/Source/platform/heap/PersistentNode.cpp
diff --git a/third_party/WebKit/Source/platform/heap/PersistentNode.cpp b/third_party/WebKit/Source/platform/heap/PersistentNode.cpp
index 329a0370df7d9394b8dc5fbec439def948f2ae43..f04607740e9eb5bf7774660a44243ba930e47d59 100644
--- a/third_party/WebKit/Source/platform/heap/PersistentNode.cpp
+++ b/third_party/WebKit/Source/platform/heap/PersistentNode.cpp
@@ -8,6 +8,15 @@
 
 namespace blink {
 
+namespace {
+
+class DummyGCBase final : public GarbageCollected<DummyGCBase> {
+public:
+    DEFINE_INLINE_TRACE() { }
+};
+
+}
+
 PersistentRegion::~PersistentRegion()
 {
     PersistentNodeSlots* slots = m_slots;
@@ -45,6 +54,21 @@ void PersistentRegion::ensurePersistentNodeSlots(void* self, TraceCallback trace
     m_slots = slots;
 }
 
+void PersistentRegion::releasePersistentNode(PersistentNode* persistentNode, ThreadState::PersistentClearCallback callback)
+{
+    ASSERT(!persistentNode->isUnused());
+    // 'self' is in use, containing the persistent wrapper object.
+    void* self = persistentNode->self();
+    if (callback) {
+        (*callback)(self);
+        ASSERT(persistentNode->isUnused());
+        return;
+    }
+    Persistent<DummyGCBase>* persistent = reinterpret_cast<Persistent<DummyGCBase>*>(self);
+    persistent->clear();
+    ASSERT(persistentNode->isUnused());
+}
+
 // This function traces all PersistentNodes. If we encounter
 // a PersistentNodeSlot that contains only freed PersistentNodes,
 // we delete the PersistentNodeSlot. This function rebuilds the free
@@ -95,13 +119,6 @@ void PersistentRegion::tracePersistentNodes(Visitor* visitor)
     ASSERT(persistentCount == m_persistentCount);
 }
 
-namespace {
-class GCObject final : public GarbageCollected<GCObject> {
-public:
-    DEFINE_INLINE_TRACE() { }
-};
-}
-
 void CrossThreadPersistentRegion::prepareForThreadStateTermination(ThreadState* threadState)
 {
     // For heaps belonging to a thread that's detaching, any cross-thread persistents
@@ -119,7 +136,7 @@ void CrossThreadPersistentRegion::prepareForThreadStateTermination(ThreadState*
                 continue;
 
             // 'self' is in use, containing the cross-thread persistent wrapper object.
-            CrossThreadPersistent<GCObject>* persistent = reinterpret_cast<CrossThreadPersistent<GCObject>*>(slots->m_slot[i].self());
+            CrossThreadPersistent<DummyGCBase>* persistent = reinterpret_cast<CrossThreadPersistent<DummyGCBase>*>(slots->m_slot[i].self());
             ASSERT(persistent);
             void* rawObject = persistent->atomicGet();
             if (!rawObject)