Widget::ShouldUseNativeFrame is now meaningful on Linux.

ui/views/widget/desktop_aura/desktop_root_window_host_x11.h

Index: ui/views/widget/desktop_aura/desktop_root_window_host_x11.h
diff --git a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.h b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.h
index c425746bfbf2319bfae63d9929da34a90dff2af8..970aa42a6020637222c89d4d1f34356de054a9b0 100644
--- a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.h
+++ b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.h
@@ -178,6 +178,9 @@ private:
   // Checks if the window manager has set a specific state.
   bool HasWMSpecProperty(const char* property) const;
 
+  // Sets whether the window's borders are provided by the window manager.
+  void SetUseNativeFrame(bool use_native_frame);
+
   // Called when another DRWHL takes capture, or when capture is released
   // entirely.
   void OnCaptureReleased();
@@ -247,6 +250,9 @@ private:
   // True if the window should stay on top of most other windows.
   bool is_always_on_top_;
 
+  // True if the window has title-bar / borders provided by the window manager.
+  bool use_native_frame_;
+
   // We are owned by the RootWindow, but we have to have a back pointer to it.
   aura::RootWindow* root_window_;