Draw transparent background on window_content() only for TYPE_CHILD.

views/widget/widget_gtk.cc

Index: views/widget/widget_gtk.cc
diff --git a/views/widget/widget_gtk.cc b/views/widget/widget_gtk.cc
index 5f0f6f87883a0cb797b4ffdbf689dc2acbf17122..7bc8d03968e3bcd8127b35aac3c409f45c26a43a 100644
--- a/views/widget/widget_gtk.cc
+++ b/views/widget/widget_gtk.cc
@@ -896,10 +896,10 @@ void WidgetGtk::OnSizeAllocate(GtkWidget* widget, GtkAllocation* allocation) {
 }
 
 gboolean WidgetGtk::OnPaint(GtkWidget* widget, GdkEventExpose* event) {
-  if (transparent_) {
+  if (transparent_ && type_ == TYPE_CHILD) {
     // Clear the background before drawing any view and native components.
     DrawTransparentBackground(widget, event);
-    if (type_ == TYPE_CHILD && !CompositePainter::IsComposited(widget_)) {
+    if (!CompositePainter::IsComposited(widget_)) {
       // Let the parent draw the content only after something is drawn on
       // the widget.
       CompositePainter::SetComposited(widget_);