Make WindowTree::SetModal() take the type.

ui/aura/mus/in_flight_change.h

 // Copyright 2015 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 UI_AURA_MUS_IN_FLIGHT_CHANGE_H_
 #define UI_AURA_MUS_IN_FLIGHT_CHANGE_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "ui/aura/window_observer.h"
+#include "ui/base/ui_base_types.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace ui {
 
 namespace mojom {
 enum class Cursor : int32_t;
 }
 
 }  // namespace ui
 
@@ skipping 279 matching lines @@
   // InFlightChange:
   void SetRevertValueFrom(const InFlightChange& change) override;
   void Revert() override;
 
  private:
   float revert_opacity_;
 
   DISALLOW_COPY_AND_ASSIGN(InFlightOpacityChange);
 };
 
-class InFlightSetModalChange : public InFlightChange {
+class InFlightSetModalTypeChange : public InFlightChange {
  public:
-  explicit InFlightSetModalChange(WindowMus* window);
-  ~InFlightSetModalChange() override;
+  InFlightSetModalTypeChange(WindowMus* window, ui::ModalType revert_value);
+  ~InFlightSetModalTypeChange() override;
 
   // InFlightChange:
   void SetRevertValueFrom(const InFlightChange& change) override;
   void Revert() override;
 
  private:
-  DISALLOW_COPY_AND_ASSIGN(InFlightSetModalChange);
+  ui::ModalType revert_modal_type_;
+
+  DISALLOW_COPY_AND_ASSIGN(InFlightSetModalTypeChange);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_IN_FLIGHT_CHANGE_H_