Oilpan: Remove most WillBe types from the code base

third_party/WebKit/Source/core/paint/PaintLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 826 matching lines @@
     // box. Otherwise, this is the LayoutInline's lines' bounding box.
     IntSize m_size;
 
     // Cached normal flow values for absolute positioned elements with static left/top values.
     LayoutUnit m_staticInlinePosition;
     LayoutUnit m_staticBlockPosition;
 
     AncestorDependentCompositingInputs m_ancestorDependentCompositingInputs;
     OwnPtr<RareAncestorDependentCompositingInputs> m_rareAncestorDependentCompositingInputs;
 
-    OwnPtrWillBePersistent<PaintLayerScrollableArea> m_scrollableArea;
+    Persistent<PaintLayerScrollableArea> m_scrollableArea;
 
     mutable OwnPtr<ClipRectsCache> m_clipRectsCache;
 
     OwnPtr<PaintLayerStackingNode> m_stackingNode;
 
     IntSize m_previousScrollOffsetAccumulationForPainting;
     RefPtr<ClipRects> m_previousPaintingClipRects;
     LayoutRect m_previousPaintDirtyRect;
 
     OwnPtr<PaintLayerRareData> m_rareData;
 };
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::PaintLayer*);
 void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif // Layer_h