Oilpan: Update comments in ImageLoader.

Source/core/loader/ImageLoader.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 120 matching lines @@
     // Used to determine whether to immediately initiate the load
     // or to schedule a microtask.
     bool shouldLoadImmediately(const KURL&) const;
 
     void willRemoveClient(ImageLoaderClient&);
 
     RawPtrWillBeMember<Element> m_element;
     ResourcePtr<ImageResource> m_image;
     // FIXME: Oilpan: We might be able to remove this Persistent hack when
     // ImageResourceClient is traceable.
-    GC_PLUGIN_IGNORE("http://crbug.com/353083")
+    GC_PLUGIN_IGNORE("http://crbug.com/383741")
     RefPtrWillBePersistent<Element> m_keepAlive;
 #if ENABLE(OILPAN)
     class ImageLoaderClientRemover {
     public:
         ImageLoaderClientRemover(ImageLoader& loader, ImageLoaderClient& client) : m_loader(loader), m_client(client) { }
         ~ImageLoaderClientRemover();
 
     private:
         ImageLoader& m_loader;
         ImageLoaderClient& m_client;
     };
     friend class ImageLoaderClientRemover;
     // Oilpan: This ImageLoader object must outlive its clients because they
-    // need to call ImageLoader::willRemoveClient before they die.
-    GC_PLUGIN_IGNORE("http://crbug.com/353083")
+    // need to call ImageLoader::willRemoveClient before they
+    // die. Non-Persistent HeapHashMap doesn't work well because weak processing
+    // for HeapHashMap is not triggered when both of ImageLoader and
+    // ImageLoaderClient are unreachable.
+    GC_PLUGIN_IGNORE("http://crbug.com/383742")
     PersistentHeapHashMap<WeakMember<ImageLoaderClient>, OwnPtr<ImageLoaderClientRemover> > m_clients;
 #else
     HashSet<ImageLoaderClient*> m_clients;
 #endif
     Timer<ImageLoader> m_derefElementTimer;
     AtomicString m_failedLoadURL;
     WeakPtr<Task> m_pendingTask; // owned by Microtask
     OwnPtr<IncrementLoadEventDelayCount> m_delayLoad;
     bool m_hasPendingLoadEvent : 1;
     bool m_hasPendingErrorEvent : 1;
     bool m_imageComplete : 1;
     bool m_loadManually : 1;
     bool m_elementIsProtected : 1;
     unsigned m_highPriorityClientCount;
 };
 
 }
 
 #endif