Make WindowTree::SetModal() take the type.

ui/aura/mus/window_port_mus.h

 // 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 UI_AURA_MUS_WINDOW_PORT_MUS_H_
 #define UI_AURA_MUS_WINDOW_PORT_MUS_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 216 matching lines @@
   void OnDeviceScaleFactorChanged(float device_scale_factor) override;
   void OnWillAddChild(Window* child) override;
   void OnWillRemoveChild(Window* child) override;
   void OnWillMoveChild(size_t current_index, size_t dest_index) override;
   void OnVisibilityChanged(bool visible) override;
   void OnDidChangeBounds(const gfx::Rect& old_bounds,
                          const gfx::Rect& new_bounds) override;
   std::unique_ptr<ui::PropertyData> OnWillChangeProperty(
       const void* key) override;
   void OnPropertyChanged(const void* key,
+                         int64_t old_value,
                          std::unique_ptr<ui::PropertyData> data) override;
 
   WindowTreeClient* window_tree_client_;
 
   Window* window_ = nullptr;
 
   // Used when this window is embedding a client.
   std::unique_ptr<ClientSurfaceEmbedder> client_surface_embedder;
 
   ServerChangeIdType next_server_change_id_ = 0;
   ServerChanges server_changes_;
 
   cc::SurfaceInfo surface_info_;
 
   ui::mojom::Cursor predefined_cursor_ = ui::mojom::Cursor::CURSOR_NULL;
 
   DISALLOW_COPY_AND_ASSIGN(WindowPortMus);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_WINDOW_PORT_MUS_H_