[heap] Refactor MC and introduce MarkCompactCollectorBase

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index 00620423fa689ef66d541c3ad5dcb6904e418916..2695b4f29bb51e84d206f0c83f5b583e99dd993c 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -793,9 +793,6 @@ class MarkCompactCollector {
   void EvacuateEpilogue();
   void EvacuatePagesInParallel();
 
-  // The number of parallel compaction tasks, including the main thread.
-  int NumberOfParallelCompactionTasks(int pages, intptr_t live_bytes);
-
   void EvacuateNewSpaceAndCandidates();
 
   void UpdatePointersAfterEvacuation();