Handle cross-thread weak persistents during global weak processing.

third_party/WebKit/Source/platform/heap/MarkingVisitor.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MarkingVisitor_h
 #define MarkingVisitor_h
 
 #include "platform/heap/MarkingVisitorImpl.h"
 
 namespace blink {
@@ skipping 39 matching lines @@
     {
         return Impl::weakTableRegistered(closure);
     }
 #endif
 
     bool ensureMarked(const void* objectPointer) override
     {
         return Impl::ensureMarked(objectPointer);
     }
 
-protected:
     void registerWeakCellWithCallback(void** cell, WeakCallback callback) override
     {
         Impl::registerWeakCellWithCallback(cell, callback);
     }
 
+protected:
     inline bool shouldMarkObject(const void* objectPointer) const
     {
         if (Mode != ThreadLocalMarking)
             return true;
 
         BasePage* page = pageFromObject(objectPointer);
         ASSERT(!page->orphaned());
         // When doing a thread local GC, the marker checks if
         // the object resides in another thread's heap. If it
         // does, the object should not be marked & traced.
         return page->terminating();
     }
 };
 
 } // namespace blink
 
 #endif