Oilpan: address ScrollableArea-induced build breakage from r194957.

Source/core/frame/RootFrameViewport.h

Index: Source/core/frame/RootFrameViewport.h
diff --git a/Source/core/frame/RootFrameViewport.h b/Source/core/frame/RootFrameViewport.h
index a0ceadb4a5df399c8daf26d96f0e661d54f31e5b..8ff5be4474a05e36013983a68c203da67ef426cf 100644
--- a/Source/core/frame/RootFrameViewport.h
+++ b/Source/core/frame/RootFrameViewport.h
@@ -20,12 +20,11 @@ class LayoutRect;
 // APIs that don't make sense on the combined viewport, the call is delegated to
 // the layout viewport. Thus, we could say this class is a decorator on the
 // FrameView scrollable area that adds pinch-zoom semantics to scrolling.
-class RootFrameViewport final : public NoBaseWillBeGarbageCollectedFinalized<RootFrameViewport>, public ScrollableArea {
+class RootFrameViewport final : public ScrollableArea {
 public:
-    DECLARE_VIRTUAL_TRACE();
-    static PassOwnPtrWillBeRawPtr<RootFrameViewport> create(ScrollableArea& visualViewport, ScrollableArea& layoutViewport)
+    static PassOwnPtr<RootFrameViewport> create(ScrollableArea& visualViewport, ScrollableArea& layoutViewport)
     {
-        return adoptPtrWillBeNoop(new RootFrameViewport(visualViewport, layoutViewport));
+        return adoptPtr(new RootFrameViewport(visualViewport, layoutViewport));
     }
 
     // ScrollableArea Implementation
@@ -65,7 +64,6 @@ public:
     // call to this class' scroll method.
     ScrollResult handleWheel(const PlatformWheelEvent&) override;
 
-
 private:
     RootFrameViewport(ScrollableArea& visualViewport, ScrollableArea& layoutViewport);
 
@@ -76,11 +74,11 @@ private:
     // animator so use this method to pull updated values when necessary.
     void updateScrollAnimator();
 
-    ScrollableArea& visualViewport() const { return *m_visualViewport; }
-    ScrollableArea& layoutViewport() const { return *m_layoutViewport; }
+    ScrollableArea& visualViewport() const { return m_visualViewport; }
+    ScrollableArea& layoutViewport() const { return m_layoutViewport; }
 
-    RawPtrWillBeMember<ScrollableArea> m_visualViewport;
-    RawPtrWillBeMember<ScrollableArea> m_layoutViewport;
+    ScrollableArea& m_visualViewport;
+    ScrollableArea& m_layoutViewport;
 };
 
 } // namespace blink