Widget::ShouldUseNativeFrame is now meaningful on Linux.

ui/views/widget/widget.cc

Index: ui/views/widget/widget.cc
diff --git a/ui/views/widget/widget.cc b/ui/views/widget/widget.cc
index 9c7c1ec5d764d44fa905a7233779af976982e096..61a20fed0bced33aee820abb161e02ec8c91a025 100644
--- a/ui/views/widget/widget.cc
+++ b/ui/views/widget/widget.cc
@@ -870,6 +870,10 @@ bool Widget::ShouldUseNativeFrame() const {
   return native_widget_->ShouldUseNativeFrame();
 }
 
+bool Widget::ShouldWindowContentsBeTransparent() const {
+  return native_widget_->ShouldWindowContentsBeTransparent();
+}
+
 void Widget::DebugToggleFrameType() {
   if (frame_type_ == FRAME_TYPE_DEFAULT) {
     frame_type_ = ShouldUseNativeFrame() ? FRAME_TYPE_FORCE_CUSTOM :