Oilpan: fix build after r351868.

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ScrollbarPainter_h
 #define ScrollbarPainter_h
 
 #include "platform/heap/Handle.h"
 #include "platform/scroll/Scrollbar.h"
 
 namespace blink {
 
 class GraphicsContext;
 class IntRect;
 class LayoutPoint;
 class LayoutRect;
 class LayoutScrollbar;
 class LayoutScrollbarPart;
 
 class ScrollbarPainter {
     STACK_ALLOCATED();
     WTF_MAKE_NONCOPYABLE(ScrollbarPainter);
 public:
-    explicit ScrollbarPainter(const LayoutScrollbar& layoutScrollbar) : m_layoutScrollbar(layoutScrollbar) { }
+    explicit ScrollbarPainter(const LayoutScrollbar& layoutScrollbar) : m_layoutScrollbar(&layoutScrollbar) { }
 
     void paintPart(GraphicsContext*, ScrollbarPart, const IntRect&);
     static void paintIntoRect(const LayoutScrollbarPart&, GraphicsContext*, const LayoutPoint& paintOffset, const LayoutRect&);
 
 private:
-    const LayoutScrollbar& m_layoutScrollbar;
+    RawPtrWillBeMember<const LayoutScrollbar> m_layoutScrollbar;
 };
 
 } // namespace blink
 
 #endif // ScrollbarPainter_h