Disable collection backing reallocation during pre finalizer

third_party/WebKit/Source/platform/heap/ThreadState.h

Index: third_party/WebKit/Source/platform/heap/ThreadState.h
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.h b/third_party/WebKit/Source/platform/heap/ThreadState.h
index 34b1ad25ece4b84fe5197863e3415a89616ff738..3c7e80197d09b5c923236f9b6b8eab5454a17210 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.h
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.h
@@ -158,6 +158,19 @@ class PLATFORM_EXPORT ThreadState {
     ThreadState* state_;
   };
 
+  class NoBackingReallocationScope final {
+    STACK_ALLOCATED();
+
+   public:
+    explicit NoBackingReallocationScope(ThreadState* state) : state_(state) {
+      state_->EnterNoBackingReallocationScope();
+    }
+    ~NoBackingReallocationScope() { state_->LeaveNoBackingReallocationScope(); }
+
+   private:
+    ThreadState* state_;
+  };
+
   static void AttachMainThread();
 
   // Associate ThreadState object with the current thread. After this
@@ -261,6 +274,11 @@ class PLATFORM_EXPORT ThreadState {
     mixins_being_constructed_count_--;
   }
   bool SweepForbidden() const { return sweep_forbidden_; }
+  bool IsBackingReallocationAllowed() const {
+    return !no_backing_reallocation_;
+  }
+  void EnterNoBackingReallocationScope() { no_backing_reallocation_ = true; }

[haraken, 2017/04/12 06:44:34]

Add DCHECK(!no_backing_reallocation_).

[keishi, 2017/04/12 09:43:53]

Done.

+  void LeaveNoBackingReallocationScope() { no_backing_reallocation_ = false; }

[haraken, 2017/04/12 06:44:34]

Add DCHECK(no_backing_reallocation_).

[keishi, 2017/04/12 09:43:53]

Done.

 
   class MainThreadGCForbiddenScope final {
     STACK_ALLOCATED();
@@ -625,6 +643,7 @@ class PLATFORM_EXPORT ThreadState {
   size_t gc_forbidden_count_;
   size_t mixins_being_constructed_count_;
   double accumulated_sweeping_time_;
+  bool no_backing_reallocation_;
 
   BaseArena* arenas_[BlinkGC::kNumberOfArenas];
   int vector_backing_arena_index_;