Support high DPI scrollbar on top level web frame.

cc/LayerChromium.cpp

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #if USE(ACCELERATED_COMPOSITING)
 #include "LayerChromium.h"
 
 #include "CCActiveAnimation.h"
@@ skipping 98 matching lines @@
     if (host && m_layerAnimationController->hasActiveAnimation())
         host->didAddAnimation();
 }
 
 void LayerChromium::setNeedsCommit()
 {
     if (m_layerTreeHost)
         m_layerTreeHost->setNeedsCommit();
 }
 
+IntRect LayerChromium::layerRectToContentRect(const WebKit::WebRect& layerRect)
+{
+    float widthScale = static_cast<float>(contentBounds().width()) / bounds().width();
+    float heightScale = static_cast<float>(contentBounds().height()) / bounds().height();
+    FloatRect contentRect(layerRect.x, layerRect.y, layerRect.width, layerRect.height);
+    contentRect.scale(widthScale, heightScale);
+    return enclosingIntRect(contentRect);
+}
+
 void LayerChromium::setParent(LayerChromium* layer)
 {
     ASSERT(!layer || !layer->hasAncestor(this));
     m_parent = layer;
     setLayerTreeHost(m_parent ? m_parent->layerTreeHost() : 0);
 }
 
 bool LayerChromium::hasAncestor(LayerChromium* ancestor) const
 {
     for (LayerChromium* layer = parent(); layer; layer = layer->parent()) {
@@ skipping 592 matching lines @@
     return Region();
 }
 
 void sortLayers(Vector<RefPtr<LayerChromium> >::iterator, Vector<RefPtr<LayerChromium> >::iterator, void*)
 {
     // Currently we don't use z-order to decide what to paint, so there's no need to actually sort LayerChromiums.
 }
 
 }
 #endif // USE(ACCELERATED_COMPOSITING)