Make WindowTree::SetModal() take the type.

ui/aura/mus/window_port_mus.cc

 // 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.
 
 #include "ui/aura/mus/window_port_mus.h"
 
 #include "base/memory/ptr_util.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/transient_window_client.h"
 #include "ui/aura/mus/client_surface_embedder.h"
@@ skipping 412 matching lines @@
   // |window_| is null if a property is set on the aura::Window before
   // Window::Init() is called. It's safe to ignore the change in this case as
   // once Window::Init() is called the Window is queried for the current set of
   // properties.
   if (!window_)
     return nullptr;
 
   return window_tree_client_->OnWindowMusWillChangeProperty(this, key);
 }
 
-void WindowPortMus::OnPropertyChanged(
-    const void* key,
-    std::unique_ptr<ui::PropertyData> data) {
+void WindowPortMus::OnPropertyChanged(const void* key,
+                                      int64_t old_value,
+                                      std::unique_ptr<ui::PropertyData> data) {
   // See comment in OnWillChangeProperty() as to why |window_| may be null.
   if (!window_)
     return;
 
   ServerChangeData change_data;
   change_data.property_name =
       GetPropertyConverter()->GetTransportNameForPropertyKey(key);
   // TODO(sky): investigate to see if we need to compare data. In particular do
   // we ever have a case where changing a property cascades into changing the
   // same property?
   if (!RemoveChangeByTypeAndData(ServerChangeType::PROPERTY, change_data))
-    window_tree_client_->OnWindowMusPropertyChanged(this, key, std::move(data));
+    window_tree_client_->OnWindowMusPropertyChanged(this, key, old_value,
+                                                    std::move(data));
 }
 
 }  // namespace aura