Oilpan: Introduce WeakProcessingVisitor

Source/platform/heap/TraceTraits.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 TraceTraits_h
 #define TraceTraits_h
 
 #include "platform/heap/GCInfo.h"
 #include "platform/heap/Heap.h"
 #include "platform/heap/InlinedGlobalMarkingVisitor.h"
@@ skipping 139 matching lines @@
     {
         AdjustAndMarkTrait<T>::mark(visitor, t);
     }
 };
 
 template<typename T> class TraceTrait<const T> : public TraceTrait<T> { };
 
 template<typename T>
 void TraceTrait<T>::trace(Visitor* visitor, void* self)
 {
-    if (visitor->isGlobalMarkingVisitor()) {
+    if (visitor->markingMode() == Visitor::GlobalMarking) {
         // Switch to inlined global marking dispatch.
         static_cast<T*>(self)->trace(InlinedGlobalMarkingVisitor(visitor));
     } else {
         static_cast<T*>(self)->trace(visitor);
     }
 }
 
 template<typename T>
 void TraceTrait<T>::trace(InlinedGlobalMarkingVisitor visitor, void* self)
 {
@@ skipping 370 matching lines @@
         // since iterating over the hash table backing will find the whole
         // chain.
         visitor->markNoTracing(node);
         return false;
     }
 };
 
 } // namespace WTF
 
 #endif