mus: Make sure window parenting happens in the window server.

services/ui/ws/platform_display.h

Index: services/ui/ws/platform_display.h
diff --git a/services/ui/ws/platform_display.h b/services/ui/ws/platform_display.h
index 96b1ca9b38b03fe73a21e1bea7f3b81dce517e7e..39299aeddd10efb5f9f336b5440c77d29abeae7a 100644
--- a/services/ui/ws/platform_display.h
+++ b/services/ui/ws/platform_display.h
@@ -13,6 +13,7 @@
 #include "base/strings/string16.h"
 #include "services/ui/display/viewport_metrics.h"
 #include "services/ui/public/interfaces/cursor.mojom.h"
+#include "ui/gfx/native_widget_types.h"
 
 namespace gfx {
 class Rect;
@@ -63,6 +64,10 @@ class PlatformDisplay {
 
   virtual const display::ViewportMetrics& GetViewportMetrics() const = 0;
 
+  // Returns the AcceleratedWidget associated with the Display. It can return
+  // kNullAcceleratedWidget if the accelerated widget is not available yet.
+  virtual gfx::AcceleratedWidget GetAcceleratedWidget() const = 0;
+
   virtual FrameGenerator* GetFrameGenerator() = 0;
 
   // Overrides factory for testing. Default (NULL) value indicates regular