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

services/ui/ws/event_dispatcher.h

Index: services/ui/ws/event_dispatcher.h
diff --git a/services/ui/ws/event_dispatcher.h b/services/ui/ws/event_dispatcher.h
index aa144e90cd481e18e57816b89082d6cd409728de..eecf4ea627de5fa7296c693c0ea8827895887aa0 100644
--- a/services/ui/ws/event_dispatcher.h
+++ b/services/ui/ws/event_dispatcher.h
@@ -14,6 +14,7 @@
 #include "base/macros.h"
 #include "services/ui/common/types.h"
 #include "services/ui/public/interfaces/event_matcher.mojom.h"
+#include "services/ui/ws/drag_cursor_updater.h"
 #include "services/ui/ws/modal_window_controller.h"
 #include "services/ui/ws/server_window_observer.h"
 #include "ui/gfx/geometry/rect_f.h"
@@ -38,7 +39,7 @@ class EventDispatcherTestApi;
 }
 
 // Handles dispatching events to the right location as well as updating focus.
-class EventDispatcher : public ServerWindowObserver {
+class EventDispatcher : public ServerWindowObserver, public DragCursorUpdater {
  public:
   enum class AcceleratorMatchPhase {
     // Both pre and post should be considered.
@@ -231,6 +232,9 @@ class EventDispatcher : public ServerWindowObserver {
   void OnWindowVisibilityChanged(ServerWindow* window) override;
   void OnWindowDestroyed(ServerWindow* window) override;
 
+  // DragCursorUpdater:
+  void OnDragCursorUpdated() override;
+
   EventDispatcherDelegate* delegate_;
 
   ServerWindow* capture_window_;