Revert of [heap] Uncommit marking deque in concurrent task.

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 356c4d5b6606e3944421417d6fecd5fadff475e7..4c12ec05dee7c0a5682f8cca8d43c6b462c39a8e 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -58,7 +58,6 @@
       compacting_(false),
       black_allocation_(false),
       have_code_to_deoptimize_(false),
-      marking_deque_(heap),
       code_flusher_(nullptr),
       sweeper_(heap) {
 }
@@ -2116,13 +2115,9 @@
   }
 }
 
-void MarkingDeque::TearDown() {
-  CancelOrWaitForUncommitTask();
-  delete backing_store_;
-}
+void MarkingDeque::TearDown() { delete backing_store_; }
 
 void MarkingDeque::StartUsing() {
-  base::LockGuard<base::Mutex> guard(&mutex_);
   if (in_use_) {
     // This can happen in mark-compact GC if the incremental marker already
     // started using the marking deque.
@@ -2142,16 +2137,11 @@
 }
 
 void MarkingDeque::StopUsing() {
-  base::LockGuard<base::Mutex> guard(&mutex_);
   DCHECK(IsEmpty());
   DCHECK(!overflowed_);
   top_ = bottom_ = mask_ = 0;
+  Uncommit();
   in_use_ = false;
-  if (FLAG_concurrent_sweeping) {
-    StartUncommitTask();
-  } else {
-    Uncommit();
-  }
 }
 
 void MarkingDeque::Clear() {
@@ -2161,7 +2151,7 @@
 }
 
 void MarkingDeque::Uncommit() {
-  DCHECK(!in_use_);
+  DCHECK(in_use_);
   bool success = backing_store_->Uncommit(backing_store_->address(),
                                           backing_store_committed_size_);
   backing_store_committed_size_ = 0;
@@ -2180,28 +2170,6 @@
   }
   if (backing_store_committed_size_ == 0) {
     V8::FatalProcessOutOfMemory("MarkingDeque::EnsureCommitted");
-  }
-}
-
-void MarkingDeque::StartUncommitTask() {
-  if (!uncommit_task_pending_) {
-    UncommitTask* task = new UncommitTask(heap_->isolate(), this);
-    uncommit_task_id_ = task->id();
-    uncommit_task_pending_ = true;
-    V8::GetCurrentPlatform()->CallOnBackgroundThread(
-        task, v8::Platform::kShortRunningTask);
-  }
-}
-
-void MarkingDeque::CancelOrWaitForUncommitTask() {
-  base::LockGuard<base::Mutex> guard(&mutex_);
-  if (!uncommit_task_pending_ ||
-      heap_->isolate()->cancelable_task_manager()->TryAbort(
-          uncommit_task_id_)) {
-    return;
-  }
-  while (uncommit_task_pending_) {
-    uncommit_task_barrier_.Wait(&mutex_);
   }
 }