Extract tree root responsibility out of HTMLImportsController.

Source/core/html/imports/LinkImport.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 18 matching lines @@
  */
 
 #include "config.h"
 #include "core/html/imports/LinkImport.h"
 
 #include "core/dom/Document.h"
 #include "core/fetch/CrossOriginAccessControl.h"
 #include "core/html/HTMLLinkElement.h"
 #include "core/html/imports/HTMLImportChild.h"
 #include "core/html/imports/HTMLImportLoader.h"
+#include "core/html/imports/HTMLImportTreeRoot.h"
 #include "core/html/imports/HTMLImportsController.h"
 
-
 namespace WebCore {
 
 PassOwnPtrWillBeRawPtr<LinkImport> LinkImport::create(HTMLLinkElement* owner)
 {
     return adoptPtrWillBeNoop(new LinkImport(owner));
 }
 
 LinkImport::LinkImport(HTMLLinkElement* owner)
     : LinkResource(owner)
     , m_child(0)
@@ skipping 30 matching lines @@
     }
 
     LinkRequestBuilder builder(m_owner);
     if (!builder.isValid()) {
         didFinish();
         return;
     }
 
     HTMLImportsController* controller = m_owner->document().importsController();
     HTMLImportLoader* loader = m_owner->document().importLoader();
-    HTMLImport* parent = loader ? static_cast<HTMLImport*>(loader->firstImport()) : static_cast<HTMLImport*>(controller);
+    HTMLImport* parent = loader ? static_cast<HTMLImport*>(loader->firstImport()) : static_cast<HTMLImport*>(controller->root());
     m_child = controller->load(parent, this, builder.build(true));
     if (!m_child) {
         didFinish();
         return;
     }
 }
 
 void LinkImport::didFinish()
 {
     if (!m_owner || !m_owner->inDocument())
@@ skipping 22 matching lines @@
 {
     return m_child && m_child->isDone() && !m_child->loaderHasError();
 }
 
 void LinkImport::trace(Visitor* visitor)
 {
     LinkResource::trace(visitor);
 }
 
 } // namespace WebCore