Made layout viewport scroll updates from compositor work like ordinary layers.

third_party/WebKit/Source/platform/graphics/GraphicsLayer.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 207 matching lines @@
     void resetTrackedPaintInvalidations();
     bool hasTrackedPaintInvalidations() const;
     void trackPaintInvalidation(const DisplayItemClient&, const IntRect&, PaintInvalidationReason);
 
     void addLinkHighlight(LinkHighlight*);
     void removeLinkHighlight(LinkHighlight*);
     // Exposed for tests
     unsigned numLinkHighlights() { return m_linkHighlights.size(); }
     LinkHighlight* getLinkHighlight(int i) { return m_linkHighlights[i]; }
 
-    void setScrollableArea(ScrollableArea*, bool isViewport);
+    void setScrollableArea(ScrollableArea*, bool isVisualViewport);
     ScrollableArea* getScrollableArea() const { return m_scrollableArea; }
 
     WebContentLayer* contentLayer() const { return m_layer.get(); }
 
     static void registerContentsLayer(WebLayer*);
     static void unregisterContentsLayer(WebLayer*);
 
     IntRect interestRect();
     void paint(const IntRect* interestRect, GraphicsContext::DisabledMode = GraphicsContext::NothingDisabled);
 
@@ skipping 141 matching lines @@
 };
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the blink namespace for ease of invocation from gdb.
 void PLATFORM_EXPORT showGraphicsLayerTree(const blink::GraphicsLayer*);
 #endif
 
 #endif // GraphicsLayer_h