Reland of "[heap] Uncommit pooled pages concurrently"

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 2628898c8622e4753b4707e5ed07c1d5e1e367db..b29eeb44bc1e28a1061b524727334566e081320c 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -778,11 +778,6 @@ class Heap {
 
   inline bool OldGenerationAllocationLimitReached();
 
-  void QueueMemoryChunkForFree(MemoryChunk* chunk);
-  void FreeQueuedChunks(MemoryChunk* list_head);
-  void FreeQueuedChunks();
-  void WaitUntilUnmappingOfFreeChunksCompleted();
-
   // Completely clear the Instanceof cache (to stop it keeping objects alive
   // around a GC).
   inline void CompletelyClearInstanceofCache();
@@ -1390,7 +1385,6 @@ class Heap {
 
  private:
   class PretenuringScope;
-  class UnmapFreeMemoryTask;
 
   // External strings table is a place where all external strings are
   // registered.  We need to keep track of such strings to properly
@@ -2208,12 +2202,6 @@ class Heap {
 
   ExternalStringTable external_string_table_;
 
-  MemoryChunk* chunks_queued_for_free_;
-
-  size_t concurrent_unmapping_tasks_active_;
-
-  base::Semaphore pending_unmapping_tasks_semaphore_;
-
   base::Mutex relocation_mutex_;
 
   int gc_callbacks_depth_;