RenderWidgetHostViewChildFrame's called a virtual in its ctor.

content/browser/frame_host/render_widget_host_view_guest.cc

Index: content/browser/frame_host/render_widget_host_view_guest.cc
diff --git a/content/browser/frame_host/render_widget_host_view_guest.cc b/content/browser/frame_host/render_widget_host_view_guest.cc
index 0c5f97b52cc41a56b2d0937512eb303bcb043275..613bacc54a8f6d454b9a6c1113bf51e6abc53400 100644
--- a/content/browser/frame_host/render_widget_host_view_guest.cc
+++ b/content/browser/frame_host/render_widget_host_view_guest.cc
@@ -65,6 +65,17 @@ class ScopedInputScaleDisabler {
 
 }  // namespace
 
+// static
+RenderWidgetHostViewGuest* RenderWidgetHostViewGuest::Create(
+    RenderWidgetHost* widget,
+    BrowserPluginGuest* guest,
+    base::WeakPtr<RenderWidgetHostViewBase> platform_view) {
+  RenderWidgetHostViewGuest* view =
+      new RenderWidgetHostViewGuest(widget, guest, platform_view);
+  view->Init();
+  return view;
+}
+
 RenderWidgetHostViewGuest::RenderWidgetHostViewGuest(
     RenderWidgetHost* widget_host,
     BrowserPluginGuest* guest,