Oilpan: tidy up CSSCustomFontData::m_fontFaceSource back ref somewhat.

third_party/WebKit/Source/core/css/CSSCustomFontData.h

 /*
  * Copyright (C) 2013 Google, Inc.
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef CSSCustomFontData_h
 #define CSSCustomFontData_h
 
 #include "core/css/CSSFontFaceSource.h"
 #include "platform/fonts/CustomFontData.h"
+#include "platform/heap/Handle.h"
 
 namespace blink {
 
 class CSSCustomFontData final : public CustomFontData {
 public:
     enum FallbackVisibility { InvisibleFallback, VisibleFallback };
 
     static PassRefPtr<CSSCustomFontData> create(RemoteFontFaceSource* source, FallbackVisibility visibility)
     {
         return adoptRef(new CSSCustomFontData(source, visibility));
@@ skipping 23 matching lines @@
 private:
     CSSCustomFontData(RemoteFontFaceSource* source, FallbackVisibility visibility)
         : m_fontFaceSource(source)
         , m_fallbackVisibility(visibility)
         , m_isLoading(false)
     {
         if (source)
             m_isLoading = source->isLoading();
     }
 
-    RemoteFontFaceSource* m_fontFaceSource;
+    // TODO(Oilpan): consider moving (Custom)FontFace hierarchy to the heap,
+    // thereby making this reference a Member<>.
+    RawPtrWillBeWeakPersistent<RemoteFontFaceSource> m_fontFaceSource;
     FallbackVisibility m_fallbackVisibility;
     mutable bool m_isLoading;
 };
 
-}
+} // namespace blink
 
 #endif // CSSCustomFontData_h