mus: Implement interwindow drag and drop

services/ui/ws/current_drag_operation_delegate.h

Index: services/ui/ws/current_drag_operation_delegate.h
diff --git a/services/ui/ws/current_drag_operation_delegate.h b/services/ui/ws/current_drag_operation_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..4a104dadcbc17b06560bfe254105691b8136936c
--- /dev/null
+++ b/services/ui/ws/current_drag_operation_delegate.h
@@ -0,0 +1,22 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SERVICES_UI_WS_CURRENT_DRAG_OPERATION_DELEGATE_H_
+#define SERVICES_UI_WS_CURRENT_DRAG_OPERATION_DELEGATE_H_
+
+namespace ui {
+namespace ws {
+
+class CurrentDragOperationDelegate {
+ public:
+  virtual ~CurrentDragOperationDelegate() {}
+
+  // Called when a drag operation is completed
+  virtual void OnDragOver(bool success) = 0;
+};
+
+}  // namespace ws
+}  // namespace ui
+
+#endif  // SERVICES_UI_WS_CURRENT_DRAG_OPERATION_DELEGATE_H_