Oilpan: improve ScrollableArea handling.

Source/core/page/Page.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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,
@@ skipping 201 matching lines @@
     virtual void settingsChanged(SettingsDelegate::ChangeType) override;
 
     RefPtrWillBeMember<PageAnimator> m_animator;
     const OwnPtr<AutoscrollController> m_autoscrollController;
     ChromeClient* m_chromeClient;
     const OwnPtrWillBeMember<DragCaretController> m_dragCaretController;
     const OwnPtrWillBeMember<DragController> m_dragController;
     const OwnPtrWillBeMember<FocusController> m_focusController;
     const OwnPtrWillBeMember<ContextMenuController> m_contextMenuController;
     const OwnPtrWillBeMember<PointerLockController> m_pointerLockController;
-    OwnPtr<ScrollingCoordinator> m_scrollingCoordinator;
+    OwnPtrWillBeMember<ScrollingCoordinator> m_scrollingCoordinator;
     const OwnPtrWillBeMember<UndoStack> m_undoStack;
 
     // Typically, the main frame and Page should both be owned by the embedder,
     // which must call Page::willBeDestroyed() prior to destroying Page. This
     // call detaches the main frame and clears this pointer, thus ensuring that
     // this field only references a live main frame.
     //
     // However, there are several locations (InspectorOverlay, SVGImage, and
     // WebPagePopupImpl) which don't hold a reference to the main frame at all
     // after creating it. These are still safe because they always create a
@@ skipping 34 matching lines @@
     // A pointer to all the interfaces provided to in-process Frames for this Page.
     // FIXME: Most of the members of Page should move onto FrameHost.
     OwnPtrWillBeMember<FrameHost> m_frameHost;
 };
 
 extern template class CORE_EXTERN_TEMPLATE_EXPORT WillBeHeapSupplement<Page>;
 
 } // namespace blink
 
 #endif // Page_h