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

webkit/compositor_bindings/web_compositor_support_impl.cc

Index: webkit/compositor_bindings/web_compositor_support_impl.cc
diff --git a/webkit/compositor_bindings/web_compositor_support_impl.cc b/webkit/compositor_bindings/web_compositor_support_impl.cc
index 067f384090e2b34bcf5fff170ae1c1693dbffbee..38e4b76d1e8e78ddbdc55c3afcc32fdc95b90574 100644
--- a/webkit/compositor_bindings/web_compositor_support_impl.cc
+++ b/webkit/compositor_bindings/web_compositor_support_impl.cc
@@ -171,4 +171,15 @@ WebTransformOperations* WebCompositorSupportImpl::createTransformOperations() {
   return new WebTransformOperationsImpl();
 }
 
+void WebCompositorSupportImpl::setDefaultWebScrollbarThemeGeometry(
+    WebScrollbarThemeGeometry* geometry) {
+  WebKit::WebScrollbarLayerImpl::setDefaultGeometry(geometry);
+}
+
+void WebCompositorSupportImpl::setDefaultThemeUsesOverlayScrollbars(
+    bool usesOverlayScrollbars) {
+  WebKit::WebScrollbarLayerImpl::setDefaultUsesOverlayScrollbars(
+    usesOverlayScrollbars);
+}
+
 }  // namespace webkit