Oilpan: address ScrollableArea-induced build breakage from r194957.

Source/core/frame/PinchViewport.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 62 matching lines @@
     , m_scale(1)
     , m_topControlsAdjustment(0)
 {
     reset();
 }
 
 PinchViewport::~PinchViewport()
 {
 }
 
-DEFINE_TRACE(PinchViewport)
-{
-    visitor->trace(m_frameHost);
-}
-
 void PinchViewport::setSize(const IntSize& size)
 {
     // When the main frame is remote, we won't have an associated frame.
     if (!mainFrame())
         return;
 
     if (m_size == size)
         return;
 
     bool autosizerNeedsUpdating =
@@ skipping 571 matching lines @@
     } else if (graphicsLayer == m_rootTransformLayer) {
         name =  "Root Transform Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink