[heap] Bound number of tasks by embedder limit instead of artificially capping

src/heap/mark-compact.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_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include <deque>
 
 #include "src/base/bits.h"
@@ skipping 309 matching lines @@
   template <class Evacuator, class Collector>
   void CreateAndExecuteEvacuationTasks(
       Collector* collector, PageParallelJob<EvacuationJobTraits>* job,
       RecordMigratedSlotVisitor* record_visitor,
       MigrationObserver* migration_observer, const intptr_t live_bytes,
       const int& abandoned_pages);
 
   // Returns whether this page should be moved according to heuristics.
   bool ShouldMovePage(Page* p, intptr_t live_bytes);
 
+  int NumberOfParallelCompactionTasks(int pages);
+  int NumberOfPointerUpdateTasks(int pages);
+
   Heap* heap_;
 };
 
 // Collector for young-generation only.
 class MinorMarkCompactCollector final : public MarkCompactCollectorBase {
  public:
   explicit MinorMarkCompactCollector(Heap* heap)
       : MarkCompactCollectorBase(heap),
         marking_deque_(heap),
         page_parallel_job_semaphore_(0) {}
@@ skipping 414 matching lines @@
   ~EvacuationScope() { collector_->set_evacuation(false); }
 
  private:
   MarkCompactCollector* collector_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_