Rework the way Widget::Init works:

chrome/browser/chromeos/login/helper.cc

Index: chrome/browser/chromeos/login/helper.cc
===================================================================
--- chrome/browser/chromeos/login/helper.cc	(revision 83020)
+++ chrome/browser/chromeos/login/helper.cc	(working copy)
@@ -109,13 +109,16 @@
   throbber->set_stop_delay_ms(0);
   gfx::Rect throbber_bounds = CalculateThrobberBounds(throbber);
 
+  throbber_widget_ = views::Widget::CreateWidget();
+  static_cast<views::WidgetGtk*>(throbber_widget_->native_widget())->
+      make_transient_to_parent();
+
+  throbber_bounds.Offset(host_view_->GetScreenBounds().origin());
   views::Widget::CreateParams params(views::Widget::CreateParams::TYPE_WINDOW);
   params.transparent = true;
-  throbber_widget_ = views::Widget::CreateWidget(params);
-  static_cast<views::WidgetGtk*>(throbber_widget_)->make_transient_to_parent();
-
-  throbber_bounds.Offset(host_view_->GetScreenBounds().origin());
-  throbber_widget_->Init(host_gtk_window, throbber_bounds);
+  params.bounds = throbber_bounds;
+  params.parent = host_gtk_window;
+  throbber_widget_->Init(params);
   throbber_widget_->SetContentsView(throbber);
   // This keeps the window from flashing at startup.
   gdk_window_set_back_pixmap(