Implement pinch-zoom scaling for main-frame scrollbars and pinch-zoom overlay scrollbars.

webkit/compositor_bindings/web_scrollbar_layer_impl.cc

 // Copyright 2012 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 "webkit/compositor_bindings/web_scrollbar_layer_impl.h"
 
 #include "cc/scrollbar_layer.h"
 #include "webkit/compositor_bindings/web_layer_impl.h"
 #include "webkit/compositor_bindings/web_to_ccscrollbar_theme_painter_adapter.h"
 
@@ skipping 21 matching lines @@
 {
     return m_layer.get();
 }
 
 void WebScrollbarLayerImpl::setScrollLayer(WebLayer* layer)
 {
     int id = layer ? static_cast<WebLayerImpl*>(layer)->layer()->id() : 0;
     static_cast<ScrollbarLayer*>(m_layer->layer())->setScrollLayerId(id);
 }
 
+void WebScrollbarLayerImpl::setDefaultGeometry(WebScrollbarThemeGeometry* geometry)
+{
+    ScrollbarLayer::setDefaultGeometry(geometry);
+}
 
+void WebScrollbarLayerImpl::setDefaultUsesOverlayScrollbars(bool usesOverlayScrollbars)
+{
+    ScrollbarLayer::setDefaultUsesOverlayScrollbars(usesOverlayScrollbars);
+}
 
 } // namespace WebKit