mash: Fix mash app shelf items; encapsulate ash property setup.

ash/public/cpp/window_properties.h

 // Copyright 2017 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 ASH_PUBLIC_CPP_WINDOW_PROPERTIES_H_
 #define ASH_PUBLIC_CPP_WINDOW_PROPERTIES_H_
 
 #include <stdint.h>
 #include <string>
 
@@ skipping 30 matching lines @@
 // A property key to store ash::WindowPinType for a window.
 // When setting this property to PINNED or TRUSTED_PINNED, the window manager
 // will try to fullscreen the window and pin it on the top of the screen. If the
 // window manager failed to do it, the property will be restored to NONE. When
 // setting this property to NONE, the window manager will restore the window.
 ASH_PUBLIC_EXPORT extern const aura::WindowProperty<mojom::WindowPinType>* const
     kWindowPinTypeKey;
 
 // Alphabetical sort.
 
+// Registers ash window properties with the MusClient's property converter.
+// Also registers various properties for mirroring to root aura::Windows.
+// This propagates ash properties set on app aura::Windows to ash, via mojo.
+void ASH_PUBLIC_EXPORT RegisterWindowPropertiesForTransportAndMirroring();
+
 }  // namespace ash
 
 #endif  // ASH_PUBLIC_CPP_WINDOW_PROPERTIES_H_