Make HTMLImportTreeNode own the whole import tree.

Source/core/html/imports/HTMLImportTreeRoot.h

Index: Source/core/html/imports/HTMLImportTreeRoot.h
diff --git a/Source/core/html/imports/HTMLImportTreeRoot.h b/Source/core/html/imports/HTMLImportTreeRoot.h
index e8774a6b82fffcde98e3d509203070a402f130e7..51ef54a299f31e3b20b5f3752b43a211252b7c42 100644
--- a/Source/core/html/imports/HTMLImportTreeRoot.h
+++ b/Source/core/html/imports/HTMLImportTreeRoot.h
@@ -11,10 +11,14 @@
 
 namespace WebCore {
 
+class HTMLImportChild;
+
 class HTMLImportTreeRoot : public HTMLImport {
 public:
     static PassOwnPtr<HTMLImportTreeRoot> create(Document*);
 
+    virtual ~HTMLImportTreeRoot();
+
     // HTMLImport
     virtual Document* document() const OVERRIDE;
     virtual bool isDone() const OVERRIDE;
@@ -23,6 +27,9 @@ public:
 
     void scheduleRecalcState();
 
+    HTMLImportChild* add(PassOwnPtr<HTMLImportChild>);
+    HTMLImportChild* find(const KURL&) const;
+
 private:
     explicit HTMLImportTreeRoot(Document*);
 
@@ -30,6 +37,10 @@ private:
 
     Document* m_document;
     Timer<HTMLImportTreeRoot> m_recalcTimer;
+
+    // List of import which has been loaded or being loaded.
+    typedef Vector<OwnPtr<HTMLImportChild> > ImportList;
+    ImportList m_imports;
 };
 
 DEFINE_TYPE_CASTS(HTMLImportTreeRoot, HTMLImport, import, import->isRoot(), import.isRoot());