[WIP]Oilpan: checking for nearly-dead observers.

Source/platform/LifecycleContextTest.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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 45 matching lines @@
 public:
     static PassOwnPtrWillBeRawPtr<TestingObserver> create(DummyContext* context)
     {
         return adoptPtrWillBeNoop(new TestingObserver(context));
     }
 
     virtual void contextDestroyed() override
     {
         LifecycleObserver::contextDestroyed();
         if (m_observerToRemoveOnDestruct) {
-            lifecycleContext()->removeObserver(m_observerToRemoveOnDestruct.get());
+            lifecycleContext()->removeObserver(m_observerToRemoveOnDestruct.get(), false);
             m_observerToRemoveOnDestruct.clear();
         }
         m_contextDestroyedCalled = true;
     }
 
     DEFINE_INLINE_TRACE()
     {
         visitor->trace(m_observerToRemoveOnDestruct);
         LifecycleObserver::trace(visitor);
     }
@@ skipping 64 matching lines @@
 
     context->notifyContextDestroyed();
     EXPECT_EQ(observer->innerObserver(), nullptr);
     context = nullptr;
     Heap::collectAllGarbage();
     EXPECT_EQ(observer->lifecycleContext(), static_cast<DummyContext*>(0));
     EXPECT_TRUE(observer->contextDestroyedCalled());
 }
 
 } // namespace blink