Made double-tap zoom work in pinch virtual viewport mode. (Blink-side)

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 999 matching lines @@
     linkHighlight->layer()->setWebLayerClient(this);
     updateChildList();
 }
 
 void GraphicsLayer::removeLinkHighlight(LinkHighlightClient* linkHighlight)
 {
     m_linkHighlights.remove(m_linkHighlights.find(linkHighlight));
     updateChildList();
 }
 
-void GraphicsLayer::setScrollableArea(ScrollableArea* scrollableArea, bool isMainFrame)
+void GraphicsLayer::setScrollableArea(ScrollableArea* scrollableArea, bool isViewport)
 {
     if (m_scrollableArea == scrollableArea)
         return;
 
     m_scrollableArea = scrollableArea;
 
-    // Main frame scrolling may involve pinch zoom and gets routed through
+    // Viewport 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)
+    if (isViewport)
         m_layer->layer()->setScrollClient(0);
     else
         m_layer->layer()->setScrollClient(this);
 }
 
 void GraphicsLayer::paint(GraphicsContext& context, const IntRect& clip)
 {
     paintGraphicsLayerContents(context, clip);
 }
 
@@ skipping 20 matching lines @@
 #ifndef NDEBUG
 void showGraphicsLayerTree(const blink::GraphicsLayer* layer)
 {
     if (!layer)
         return;
 
     String output = layer->layerTreeAsText(blink::LayerTreeIncludesDebugInfo);
     fprintf(stderr, "%s\n", output.utf8().data());
 }
 #endif