Add system modals to the proper container in mus+ash.

ui/aura/mus/window_manager_delegate.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_WINDOW_MANAGER_DELEGATE_H_
 #define UI_AURA_MUS_WINDOW_MANAGER_DELEGATE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 73 matching lines @@
 
   // A client requested the shared property named |name| to change to
   // |new_data|. Return true to allow the change to |new_data|, false
   // otherwise. If true is returned the property is set via
   // PropertyConverter::SetPropertyFromTransportValue().
   virtual bool OnWmSetProperty(
       Window* window,
       const std::string& name,
       std::unique_ptr<std::vector<uint8_t>>* new_data) = 0;
 
+  // A client requested the modal type to be changed to |type|.
+  virtual void OnWmSetModalType(Window* window, ui::ModalType type) = 0;
+
   // A client requested to change focusibility of |window|. We currently assume
   // this always succeeds.
   virtual void OnWmSetCanFocus(Window* window, bool can_focus) = 0;
 
   // A client has requested a new top level window. The delegate should create
   // and parent the window appropriately and return it. |properties| is the
   // supplied properties from the client requesting the new window. The
   // delegate may modify |properties| before calling NewWindow(), but the
   // delegate does *not* own |properties|, they are valid only for the life
   // of OnWmCreateTopLevelWindow(). |window_type| is the type of window
@@ skipping 52 matching lines @@
   // window.
   virtual void OnWmDeactivateWindow(Window* window) = 0;
 
  protected:
   virtual ~WindowManagerDelegate() {}
 };
 
 }  // namespace ui
 
 #endif  // UI_AURA_MUS_WINDOW_MANAGER_DELEGATE_H_