Set default pinch viewport overlay scrollbar thickness in WebPreferences.

webkit/renderer/webpreferences_renderer.cc

Index: webkit/renderer/webpreferences_renderer.cc
diff --git a/webkit/renderer/webpreferences_renderer.cc b/webkit/renderer/webpreferences_renderer.cc
index f484622345117540a9d013d0a3c7839cafc2bd8b..e7c39a74955972466496a79becd21333cbd1eac6 100644
--- a/webkit/renderer/webpreferences_renderer.cc
+++ b/webkit/renderer/webpreferences_renderer.cc
@@ -341,6 +341,9 @@ void ApplyWebPreferences(const WebPreferences& prefs, WebView* web_view) {
       prefs.experimental_websocket_enabled);
   settings->setPinchVirtualViewportEnabled(
       prefs.pinch_virtual_viewport_enabled);
+
+  settings->setPinchOverlayScrollbarThickness(
+      prefs.pinch_overlay_scrollbar_thickness);
 }