Insert pinch zoom virtual viewport layers to graphics layer tree.

public/platform/WebCompositorSupport.h

 /*
  * Copyright (C) 2012 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:
  *
  * 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 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebCompositorSupport_h
 #define WebCompositorSupport_h
 
 #include "WebAnimation.h"
 #include "WebCommon.h"
 #include "WebLayerTreeView.h"
+#include "WebScrollbar.h"
 #include "WebScrollbarThemePainter.h"
 
 namespace WebKit {
 
 class WebAnimationCurve;
 class WebCompositorOutputSurface;
 class WebContentLayer;
 class WebContentLayerClient;
 class WebExternalTextureLayer;
 class WebExternalTextureLayerClient;
 class WebFloatAnimationCurve;
 class WebGraphicsContext3D;
 class WebImageLayer;
 class WebLayer;
-class WebScrollbar;
 class WebScrollbarLayer;
 class WebScrollbarThemeGeometry;
 class WebSolidColorLayer;
 class WebThread;
 class WebTransformAnimationCurve;
 class WebTransformOperations;
 
 class WebCompositorSupport {
 public:
     // Creates an output surface for the compositor backed by a 3d context.
@@ skipping 11 matching lines @@
     virtual WebExternalTextureLayer* createExternalTextureLayer(WebExternalTextureLayerClient* = 0) { return 0; }
 
     virtual WebExternalTextureLayer* createExternalTextureLayerForMailbox(WebExternalTextureLayerClient*) { return 0; }
 
     virtual WebImageLayer* createImageLayer() { return 0; }
 
     virtual WebSolidColorLayer* createSolidColorLayer() { return 0; }
 
     virtual WebScrollbarLayer* createScrollbarLayer(WebScrollbar*, WebScrollbarThemePainter, WebScrollbarThemeGeometry*) { return 0; }
 
+    virtual WebScrollbarLayer* createScrollbarLayer(WebLayer* scrollLayer, WebScrollbar::Orientation, size_t thickness) { return 0; }
+
 
     // Animation ----------------------------------------------------
 
     virtual WebAnimation* createAnimation(const WebAnimationCurve&, WebAnimation::TargetProperty, int animationId = 0) { return 0; }
 
     virtual WebFloatAnimationCurve* createFloatAnimationCurve() { return 0; }
 
     virtual WebTransformAnimationCurve* createTransformAnimationCurve() { return 0; }
 
     virtual WebTransformOperations* createTransformOperations() { return 0; }
 
 
 protected:
     virtual ~WebCompositorSupport() { }
 };
 
 }
 
 #endif // WebCompositorSupport_h