[oilpan] Resurrect a loop-back persistent handle in RefCountedHeapAllocated

Source/heap/tests/HeapTest.cpp

Index: Source/heap/tests/HeapTest.cpp
diff --git a/Source/heap/tests/HeapTest.cpp b/Source/heap/tests/HeapTest.cpp
index c1bd56f8db226ecb9217606d9af3223584053420..c7776ee5438f151f38e4966f70df4a061ce64ec0 100644
--- a/Source/heap/tests/HeapTest.cpp
+++ b/Source/heap/tests/HeapTest.cpp
@@ -348,6 +348,8 @@ public:
 
     static void refCountedHeapAllocatedTest()
     {
+        RefCountedAndHeapAllocated::s_destructorCalls = 0;
+        RefCountedAndHeapAllocated2::s_destructorCalls = 0;
         {
             RefPtr<RefCountedAndHeapAllocated> o1 = RefCountedAndHeapAllocated::create();
             RefPtr<RefCountedAndHeapAllocated> o2 = RefCountedAndHeapAllocated::create();
@@ -367,6 +369,56 @@ public:
         ASSERT_EQ(2, RefCountedAndHeapAllocated2::s_destructorCalls);
     }
 
+    static void refCountedHeapAllocatedWithHandlesTest()
+    {
+        RefCountedAndHeapAllocated::s_destructorCalls = 0;
+        RefCountedAndHeapAllocated2::s_destructorCalls = 0;
+        {
+            HandleScope scope;
+            Handle<RefCountedAndHeapAllocated> handle1;
+            Handle<RefCountedAndHeapAllocated> handle2;
+            {
+                RefPtr<RefCountedAndHeapAllocated> object1 = RefCountedAndHeapAllocated::create();
+                RefPtr<RefCountedAndHeapAllocated> object2 = RefCountedAndHeapAllocated::create();
+                handle1 = Handle<RefCountedAndHeapAllocated>(object1.get());
+                handle2 = Handle<RefCountedAndHeapAllocated>(object2.get());
+                void* objects[2] = { object1.get(), object2.get() };
+                RefCountedHeapAllocatedHandleVisitor visitor(2, objects);
+                PersistentBase::visitRoots(&visitor);
+                ASSERT_TRUE(visitor.validate());
+
+                Heap::collectGarbage();
+                ASSERT_EQ(0, RefCountedAndHeapAllocated::s_destructorCalls);
+            }
+            Heap::collectGarbage();
+            ASSERT_EQ(0, RefCountedAndHeapAllocated::s_destructorCalls);
+
+            // At this point, the reference counts of object1 and object2 are 0.
+            // Only handle1 and handle2 keep references to object1 and object2.
+            void* objects[] = { };
+            RefCountedHeapAllocatedHandleVisitor visitor(0, objects);
+            PersistentBase::visitRoots(&visitor);
+            ASSERT_TRUE(visitor.validate());
+
+            {
+                RefPtr<RefCountedAndHeapAllocated> object1(handle1.raw());
+                RefPtr<RefCountedAndHeapAllocated> object2(handle2.raw());
+                void* objects[2] = { object1.get(), object2.get() };
+                RefCountedHeapAllocatedHandleVisitor visitor(2, objects);
+                PersistentBase::visitRoots(&visitor);
+                ASSERT_TRUE(visitor.validate());
+
+                Heap::collectGarbage();
+                ASSERT_EQ(0, RefCountedAndHeapAllocated::s_destructorCalls);
+            }
+
+            Heap::collectGarbage();
+            ASSERT_EQ(0, RefCountedAndHeapAllocated::s_destructorCalls);
+        }
+        Heap::collectGarbage();
+        ASSERT_EQ(2, RefCountedAndHeapAllocated::s_destructorCalls);
+    }
+
     static void markTest();
     static void deepTest();
     static void wideTest();
@@ -584,6 +636,11 @@ TEST(heap, RefCountedHeapAllocated)
     HeapTester::refCountedHeapAllocatedTest();
 }
 
+TEST(heap, RefCountedHeapAllocatedWithHandles)
+{
+    HeapTester::refCountedHeapAllocatedWithHandlesTest();
+}
+
 TEST(heap, Mark)
 {
     HeapTester::markTest();