mus: Keep track of the drag cursor during DnD operations.

services/ui/ws/event_dispatcher_delegate.h

Index: services/ui/ws/event_dispatcher_delegate.h
diff --git a/services/ui/ws/event_dispatcher_delegate.h b/services/ui/ws/event_dispatcher_delegate.h
index 82a5216064a72957bd81a10924021c0fadb48539..eb0c51ad9ed583cb4de7e935a851bc518a5d0b84 100644
--- a/services/ui/ws/event_dispatcher_delegate.h
+++ b/services/ui/ws/event_dispatcher_delegate.h
@@ -46,6 +46,10 @@ class EventDispatcherDelegate {
   // longer a ServerWindow holding capture.
   virtual void ReleaseNativeCapture() = 0;
 
+  // Called when EventDispatcher has a new value for the cursor and our
+  // delegate should perform the native updates.
+  virtual void UpdateNativeCursorFromDispatcher() = 0;
+
   // Called when |window| has lost capture. The native display may still be
   // holding capture. The delegate should not change native display capture.
   // ReleaseNativeCapture() is invoked if appropriate.