[heap] Make the current GCCallbackFlags are part of {Heap}.

src/heap/incremental-marking.h

 // Copyright 2012 the V8 project 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 V8_HEAP_INCREMENTAL_MARKING_H_
 #define V8_HEAP_INCREMENTAL_MARKING_H_
 
 #include "src/execution.h"
 #include "src/heap/mark-compact.h"
 #include "src/objects.h"
@@ skipping 63 matching lines @@
   }
 
   GCRequestType request_type() const { return request_type_; }
 
   bool CanBeActivated();
 
   bool ShouldActivateEvenWithoutIdleNotification();
 
   bool WasActivated();
 
-  void Start(int flags,
-             const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags,
-             const char* reason = nullptr);
+  void Start(const char* reason = nullptr);
 
   void MarkObjectGroups();
 
   void UpdateMarkingDequeAfterScavenge();
 
   void Hurry();
 
   void Finalize();
 
   void Stop();
@@ skipping 95 matching lines @@
   }
 
   void ClearIdleMarkingDelayCounter();
 
   bool IsIdleMarkingDelayCounterLimitReached();
 
   INLINE(static void MarkObject(Heap* heap, HeapObject* object));
 
   Heap* heap() const { return heap_; }
 
-  GCCallbackFlags CallbackFlags() const { return gc_callback_flags_; }
-
  private:
   int64_t SpaceLeftInOldSpace();
 
   void SpeedUp();
 
   void ResetStepCounters();
 
   void StartMarking();
 
   void ActivateIncrementalWriteBarrier(PagedSpace* space);
@@ skipping 38 matching lines @@
   int unscanned_bytes_of_large_object_;
 
   bool was_activated_;
 
   bool weak_closure_was_overapproximated_;
 
   int weak_closure_approximation_rounds_;
 
   GCRequestType request_type_;
 
-  GCCallbackFlags gc_callback_flags_;
-
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_INCREMENTAL_MARKING_H_