Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/html/imports/HTMLImportChild.h

 /*
  * 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 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef HTMLImportChild_h
 #define HTMLImportChild_h
 
 #include "core/fetch/RawResource.h"
 #include "core/fetch/ResourceOwner.h"
 #include "core/html/imports/HTMLImport.h"
+#include "heap/Handle.h"
 #include "platform/weborigin/KURL.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
 class CustomElementMicrotaskImportStep;
 class HTMLImportLoader;
 class HTMLImportChildClient;
 class HTMLLinkElement;
 
@@ skipping 42 matching lines @@
     // HTMLImportChild owns the resource so that the contents of prefetched Resource doesn't go away.
     virtual void responseReceived(Resource*, const ResourceResponse&) OVERRIDE { }
     virtual void dataReceived(Resource*, const char*, int) OVERRIDE { }
     virtual void notifyFinished(Resource*) OVERRIDE { }
 
     void didFinish();
     void createLoader();
     void shareLoader(HTMLImportChild*);
     void ensureLoader();
 
+#if ENABLE(OILPAN)
+    Persistent<Document> m_master;

[haraken, 2014/04/24 04:18:43]

Won't this cause a cycle? You are replacing a RawPtr with a Persistent.

Probably you can keep this as a raw pointer and clear it when ~Document() calls
m_importsController->wasDetachedFrom(*this).

[Mads Ager (chromium), 2014/04/24 10:57:36]

This will be no worse than it was before. The HTMLImportChild increments the
Document guardRef in its constructor and decrements it in the destructor. The
persistent here has the same effect. The Document cannot die until the
ImportChild is dead. We should indeed get rid of the persistent in a followup
change and it should be a traced member.

+#else
     Document& m_master;
+#endif
     KURL m_url;
     CustomElementMicrotaskImportStep* m_customElementMicrotaskStep;
     HTMLImportLoader* m_loader;
     HTMLImportChildClient* m_client;
 };
 
 inline HTMLImportChild* toHTMLImportChild(HTMLImport* import)
 {
     ASSERT(!import || import->isChild());
     return static_cast<HTMLImportChild*>(import);
 }
 
 } // namespace WebCore
 
 #endif // HTMLImportChild_h