Reland of "[heap] Uncommit pooled pages concurrently"

src/heap/heap.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_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 760 matching lines @@
   // An object should be promoted if the object has survived a
   // scavenge operation.
   inline bool ShouldBePromoted(Address old_address, int object_size);
 
   void ClearNormalizedMapCaches();
 
   void IncrementDeferredCount(v8::Isolate::UseCounterFeature feature);
 
   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();
 
   inline uint32_t HashSeed();
 
   inline int NextScriptId();
 
   inline void SetArgumentsAdaptorDeoptPCOffset(int pc_offset);
   inline void SetConstructStubDeoptPCOffset(int pc_offset);
@@ skipping 587 matching lines @@
   // Report heap statistics.
   void ReportHeapStatistics(const char* title);
   void ReportCodeStatistics(const char* title);
 #endif
 #ifdef ENABLE_SLOW_DCHECKS
   int CountHandlesForObject(Object* object);
 #endif
 
  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
   // finalize them.
   class ExternalStringTable {
    public:
     // Registers an external string.
     inline void AddString(String* string);
 
     inline void Iterate(ObjectVisitor* v);
@@ skipping 797 matching lines @@
 
   // Currently set GC flags that are respected by all GC components.
   int current_gc_flags_;
 
   // Currently set GC callback flags that are used to pass information between
   // the embedder and V8's GC.
   GCCallbackFlags current_gc_callback_flags_;
 
   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_;
 
   bool deserialization_complete_;
 
   StrongRootsList* strong_roots_list_;
 
   ArrayBufferTracker* array_buffer_tracker_;
 
@@ skipping 422 matching lines @@
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_