Oilpan: Prepare to move ImageLoader and its subclasses to Oilpan heap.

Source/core/loader/ImageLoader.h

Index: Source/core/loader/ImageLoader.h
diff --git a/Source/core/loader/ImageLoader.h b/Source/core/loader/ImageLoader.h
index 1e0cdc426af7bc28729f3a8821b069c885551461..7ed593872f8c2c7482146ad0aa7b5796f205d52b 100644
--- a/Source/core/loader/ImageLoader.h
+++ b/Source/core/loader/ImageLoader.h
@@ -55,10 +55,11 @@ class RenderImageResource;
 template<typename T> class EventSender;
 typedef EventSender<ImageLoader> ImageEventSender;
 
-class ImageLoader : public ImageResourceClient {
+class ImageLoader : public NoBaseWillBeGarbageCollectedFinalized<ImageLoader>, public ImageResourceClient {
 public:
     explicit ImageLoader(Element*);
     virtual ~ImageLoader();
+    void trace(Visitor*);
 
     enum LoadType {
         LoadNormally,
@@ -133,9 +134,14 @@ private:
 
     void willRemoveClient(ImageLoaderClient&);
 
-    Element* m_element;
+    RawPtrWillBeMember<Element> m_element;
     ResourcePtr<ImageResource> m_image;
 #if ENABLE(OILPAN)
+    // FIXME: Oilpan: We might be able to remove this hack when
+    // ImageResourceClient is traceable.
+    GC_PLUGIN_IGNORE("http://crbug.com/353083")
+    Persistent<ImageLoader> m_keepAlive;
+
     class ImageLoaderClientRemover {
     public:
         ImageLoaderClientRemover(ImageLoader& loader, ImageLoaderClient& client) : m_loader(loader), m_client(client) { }
@@ -146,6 +152,9 @@ private:
         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")
     PersistentHeapHashMap<WeakMember<ImageLoaderClient>, OwnPtr<ImageLoaderClientRemover> > m_clients;

[haraken, 2014/06/09 11:12:34]

Why does this need to be a Persistent? It looks strange to trace a persistent
handle.

[tkent, 2014/06/10 01:43:09]

The comment above explains it.
Tracing this is my bad.  I'll remove it.

 #else
     HashSet<ImageLoaderClient*> m_clients;