StackFrameDepth should be managed per ThreadHeap

third_party/WebKit/Source/platform/heap/Visitor.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 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef Visitor_h
 #define Visitor_h
 
 #include "platform/PlatformExport.h"
 #include "platform/heap/GarbageCollected.h"
+#include "platform/heap/StackFrameDepth.h"
 #include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
 #include "wtf/Forward.h"
 #include "wtf/HashTraits.h"
 #include "wtf/TypeTraits.h"
 #include <memory>
 
 namespace blink {
 
 template<typename T> class GarbageCollected;
@@ skipping 64 matching lines @@
 #define DECLARE_TRACE() DECLARE_TRACE_IMPL(EMPTY_MACRO_ARGUMENT)
 #define DECLARE_VIRTUAL_TRACE() DECLARE_TRACE_IMPL(virtual)
 #define DEFINE_INLINE_TRACE() DEFINE_INLINE_TRACE_IMPL(EMPTY_MACRO_ARGUMENT)
 #define DEFINE_INLINE_VIRTUAL_TRACE() DEFINE_INLINE_TRACE_IMPL(virtual)
 
 // VisitorHelper contains common implementation of Visitor helper methods.
 //
 // VisitorHelper avoids virtual methods by using CRTP.
 // c.f. http://en.wikipedia.org/wiki/Curiously_Recurring_Template_Pattern
 template<typename Derived>
-class VisitorHelper {
+class VisitorHelper : public StackFrameDepth {

[haraken, 2016/09/06 13:03:11]

This looks like a weird class design.

This is okay in this CL but consider making Visitor(Helper) own the
StackFrameDepth.

 public:
     VisitorHelper(ThreadState* state) : m_state(state) { }
 
     // One-argument templated mark method. This uses the static type of
     // the argument to get the TraceTrait. By default, the mark method
     // of the TraceTrait just calls the virtual two-argument mark method on this
     // visitor, where the second argument is the static trace method of the trait.
     template<typename T>
     void mark(T* t)
     {
@@ skipping 197 matching lines @@
 private:
     static Visitor* fromHelper(VisitorHelper<Visitor>* helper) { return static_cast<Visitor*>(helper); }
 
     ThreadState* m_state;
     const MarkingMode m_markingMode;
 };
 
 } // namespace blink
 
 #endif // Visitor_h