Add unit test for non-leftmost GC mixin instance.

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 4578 matching lines @@
     MultipleMixins() : m_obj(IntWrapper::create(102)) { }
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
         visitor->trace(m_obj);
         MixinA::trace(visitor);
         MixinB::trace(visitor);
     }
     Member<IntWrapper> m_obj;
 };
 
+class DerivedMultipleMixins : public MultipleMixins {
+public:
+    DerivedMultipleMixins() : m_obj(IntWrapper::create(103)) { }
+
+    DEFINE_INLINE_VIRTUAL_TRACE()
+    {
+        s_traceCalled++;
+        visitor->trace(m_obj);
+        MultipleMixins::trace(visitor);
+    }
+
+    static int s_traceCalled;
+
+private:
+    Member<IntWrapper> m_obj;
+};
+
+int DerivedMultipleMixins::s_traceCalled = 0;
+
 static const bool s_isMixinTrue = IsGarbageCollectedMixin<MultipleMixins>::value;
 static const bool s_isMixinFalse = IsGarbageCollectedMixin<IntWrapper>::value;
 
 TEST(HeapTest, MultipleMixins)
 {
     EXPECT_TRUE(s_isMixinTrue);
     EXPECT_FALSE(s_isMixinFalse);
 
     clearOutOldGarbage();
     IntWrapper::s_destructorCalls = 0;
     MultipleMixins* obj = new MultipleMixins();
     {
         Persistent<MixinA> a = obj;
         preciselyCollectGarbage();
         EXPECT_EQ(0, IntWrapper::s_destructorCalls);
     }
     {
         Persistent<MixinB> b = obj;
         preciselyCollectGarbage();
         EXPECT_EQ(0, IntWrapper::s_destructorCalls);
     }
     preciselyCollectGarbage();
     EXPECT_EQ(3, IntWrapper::s_destructorCalls);
 }
 
+TEST(HeapTest, DerivedMultipleMixins)
+{
+    clearOutOldGarbage();
+    IntWrapper::s_destructorCalls = 0;
+    DerivedMultipleMixins::s_traceCalled = 0;
+
+    DerivedMultipleMixins* obj = new DerivedMultipleMixins();
+    {
+        Persistent<MixinA> a = obj;
+        preciselyCollectGarbage();
+        EXPECT_EQ(0, IntWrapper::s_destructorCalls);
+        EXPECT_EQ(1, DerivedMultipleMixins::s_traceCalled);
+    }
+    {
+        Persistent<MixinB> b = obj;
+        preciselyCollectGarbage();
+        EXPECT_EQ(0, IntWrapper::s_destructorCalls);
+        EXPECT_EQ(2, DerivedMultipleMixins::s_traceCalled);
+    }
+    preciselyCollectGarbage();
+    EXPECT_EQ(4, IntWrapper::s_destructorCalls);
+}
+
 class GCParkingThreadTester {
 public:
     static void test()
     {
         OwnPtr<WebThread> sleepingThread = adoptPtr(Platform::current()->createThread("SleepingThread"));
         sleepingThread->taskRunner()->postTask(BLINK_FROM_HERE, new Task(threadSafeBind(sleeperMainFunc)));
 
         // Wait for the sleeper to run.
         while (!s_sleeperRunning) {
             Platform::current()->yieldCurrentThread();
@@ skipping 1814 matching lines @@
     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