Disable collection backing reallocation during pre finalizer

third_party/WebKit/Source/platform/heap/HeapTest.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1481 matching lines @@
     for (int i = 0; i < 32; ++i)
       LargeHeapObject::Create();
   }
 
   DEFINE_INLINE_TRACE() {}
 
  private:
   Persistent<IntWrapper>* wrapper_;
 };
 
+class PreFinalizerBackingReallocationForbiddenCheck
+    : public GarbageCollectedFinalized<
+          PreFinalizerBackingReallocationForbiddenCheck> {
+  USING_PRE_FINALIZER(PreFinalizerBackingReallocationForbiddenCheck, Dispose);
+
+ public:
+  PreFinalizerBackingReallocationForbiddenCheck() {
+    vector_.push_back(nullptr);
+    EXPECT_LT(0ul, vector_.Capacity());
+    for (int i = 1; i <= 32; ++i) {
+      map_.insert(i, nullptr);
+    }
+    EXPECT_LT(32ul, map_.Capacity());
+  }
+
+  void Dispose() {
+    vector_.Clear();
+    EXPECT_LT(0ul, vector_.Capacity());
+    for (int i = 1; i <= 32; ++i) {
+      map_.erase(i);
+    }
+    EXPECT_LT(32ul, map_.Capacity());
+    // Clearing is OK inside a pre finalizer.
+    map_.Clear();
+    EXPECT_EQ(0ul, map_.Capacity());
+  }
+
+  DEFINE_INLINE_TRACE() {
+    visitor->Trace(vector_);
+    visitor->Trace(map_);
+  }
+
+ private:
+  HeapVector<Member<IntWrapper>> vector_;
+  HeapHashMap<int, Member<IntWrapper>> map_;
+};
+
+TEST(HeapTest, BackingReallocationForbidden) {
+  new PreFinalizerBackingReallocationForbiddenCheck();
+  PreciselyCollectGarbage();
+}
+
 TEST(HeapTest, Transition) {
   {
     RefCountedAndGarbageCollected::destructor_calls_ = 0;
     Persistent<RefCountedAndGarbageCollected> ref_counted =
         RefCountedAndGarbageCollected::Create();
     PreciselyCollectGarbage();
     EXPECT_EQ(0, RefCountedAndGarbageCollected::destructor_calls_);
   }
   PreciselyCollectGarbage();
   EXPECT_EQ(1, RefCountedAndGarbageCollected::destructor_calls_);
@@ skipping 5044 matching lines @@
     map.insert(key, IntWrapper::Create(i));
   }
 
   EXPECT_FALSE(string.Impl()->HasOneRef());
   map.Clear();
 
   EXPECT_TRUE(string.Impl()->HasOneRef());
 }
 
 }  // namespace blink