Zero-initialize persistent heap vector inline backing buffers.

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 6416 matching lines @@
     EXPECT_FALSE(crossThreadWeakPersistent.get());
     {
         SafePointAwareMutexLocker recursiveMutexLocker(recursiveMutex());
         EXPECT_EQ(1, DestructorLockingObject::s_destructorCalls);
     }
 
     wakeWorkerThread();
     parkMainThread();
 }
 
+class TestPersistentHeapVectorWithUnusedSlots : public PersistentHeapVector<VectorObject, 16> {
+public:
+    void checkUnused()
+    {
+        checkUnusedSlots(end(), end() + (capacity() - size()));
+    }
+};
+
+TEST(HeapTest, TestPersistentHeapVectorWithUnusedSlots)
+{
+    TestPersistentHeapVectorWithUnusedSlots vector1;
+    TestPersistentHeapVectorWithUnusedSlots vector2(vector1);
+
+    vector1.checkUnused();
+    vector2.checkUnused();
+
+    vector2.append(VectorObject());
+    vector2.checkUnused();
+
+    EXPECT_EQ(0u, vector1.size());
+
+    EXPECT_EQ(1u, vector2.size());
+// TODO(Oilpan): when Vector.h's contiguous container support no longer disables
+// Vector<>s with inline capacity, remove.
+#if !defined(ANNOTATE_CONTIGUOUS_CONTAINER)
+    EXPECT_EQ(16u, vector1.capacity());
+    EXPECT_EQ(16u, vector2.capacity());
+#endif
+}
+
 } // namespace blink