Reland of "[heap] Parallel newspace evacuation, semispace copy, and compaction \o/"

src/heap/array-buffer-tracker.h

 // Copyright 2015 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_ARRAY_BUFFER_TRACKER_H_
 #define V8_HEAP_ARRAY_BUFFER_TRACKER_H_
 
 #include <map>
 
+#include "src/base/platform/mutex.h"
 #include "src/globals.h"
 
 namespace v8 {
 namespace internal {
 
 // Forward declarations.
 class Heap;
 class JSArrayBuffer;
 
 class ArrayBufferTracker {
@@ skipping 20 matching lines @@
   void FreeDead(bool from_scavenge);
 
   // Prepare for a new scavenge phase. A new marking phase is implicitly
   // prepared by finishing the previous one.
   void PrepareDiscoveryInNewSpace();
 
   // An ArrayBuffer moved from new space to old space.
   void Promote(JSArrayBuffer* buffer);
 
  private:
+  base::Mutex mutex_;
   Heap* heap_;
 
   // |live_array_buffers_| maps externally allocated memory used as backing
   // store for ArrayBuffers to the length of the respective memory blocks.
   //
   // At the beginning of mark/compact, |not_yet_discovered_array_buffers_| is
   // a copy of |live_array_buffers_| and we remove pointers as we discover live
   // ArrayBuffer objects during marking. At the end of mark/compact, the
   // remaining memory blocks can be freed.
   std::map<void*, size_t> live_array_buffers_;
   std::map<void*, size_t> not_yet_discovered_array_buffers_;
 
   // To be able to free memory held by ArrayBuffers during scavenge as well, we
   // have a separate list of allocated memory held by ArrayBuffers in new space.
   //
   // Since mark/compact also evacuates the new space, all pointers in the
   // |live_array_buffers_for_scavenge_| list are also in the
   // |live_array_buffers_| list.
   std::map<void*, size_t> live_array_buffers_for_scavenge_;
   std::map<void*, size_t> not_yet_discovered_array_buffers_for_scavenge_;
 };
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_HEAP_ARRAY_BUFFER_TRACKER_H_