Made PinchViewport a ScrollableArea

Source/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1164 matching lines @@
 
 void GraphicsLayer::setScrollableArea(ScrollableArea* scrollableArea, bool isMainFrame)
 {
     if (m_scrollableArea == scrollableArea)
         return;
 
     m_scrollableArea = scrollableArea;
 
     // Main frame scrolling may involve pinch zoom and gets routed through
     // WebViewImpl explicitly rather than via GraphicsLayer::didScroll.
+    // TODO(bokan): With pinch virtual viewport the special case will no
+    // longer be needed, remove once old-style pinch is gone.
     if (isMainFrame)
         m_layer->layer()->setScrollClient(0);
     else
         m_layer->layer()->setScrollClient(this);
 }
 
 void GraphicsLayer::paint(GraphicsContext& context, const IntRect& clip)
 {
     paintGraphicsLayerContents(context, clip);
 }
@@ skipping 21 matching lines @@
 #ifndef NDEBUG
 void showGraphicsLayerTree(const WebCore::GraphicsLayer* layer)
 {
     if (!layer)
         return;
 
     String output = layer->layerTreeAsText(WebCore::LayerTreeIncludesDebugInfo);
     fprintf(stderr, "%s\n", output.utf8().data());
 }
 #endif