Concurrently unmap free pages.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 415e7d0c5ee569ea458263beb294efc1245cead9..88d49cff421d7389d6c7df9c8c9b7787bd32bf17 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1442,7 +1442,9 @@ class Heap {
 
   void QueueMemoryChunkForFree(MemoryChunk* chunk);
   void FilterStoreBufferEntriesOnAboutToBeFreedPages();
+  void FreeQueuedChunks(MemoryChunk* list_head);
   void FreeQueuedChunks();
+  void WaitUntilUnmappingOfFreeChunksCompleted();
 
   int gc_count() const { return gc_count_; }
 
@@ -1681,6 +1683,8 @@ class Heap {
  private:
   Heap();
 
+  class UnmapFreeMemoryTask;

[Michael Lippautz, 2015/08/21 12:28:58]

Move to the top of the private section.

[Hannes Payer (out of office), 2015/08/21 12:56:04]

Done.

+
   int current_gc_flags() { return current_gc_flags_; }
   void set_current_gc_flags(int flags) {
     current_gc_flags_ = flags;
@@ -2299,6 +2303,8 @@ class Heap {
 
   MemoryChunk* chunks_queued_for_free_;
 
+  base::Semaphore pending_unmap_job_semaphore_;
+
   base::Mutex relocation_mutex_;
 
   int gc_callbacks_depth_;