mash: Relay some Chrome aura window properties to Ash.

ui/views/mus/mus_property_mirror.h

Index: ui/views/mus/mus_property_mirror.h
diff --git a/ui/views/mus/mus_property_mirror.h b/ui/views/mus/mus_property_mirror.h
new file mode 100644
index 0000000000000000000000000000000000000000..606c6e5037ee38cc4dcf7661b587fc4cfe91d29d
--- /dev/null
+++ b/ui/views/mus/mus_property_mirror.h
@@ -0,0 +1,24 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.

[sky, 2017/01/27 20:10:45]

2017

[msw, 2017/01/27 21:19:25]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_VIEWS_MUS_MUS_PROPERTY_MIRROR_H_
+#define UI_VIEWS_MUS_MUS_PROPERTY_MIRROR_H_
+
+#include "ui/views/mus/mus_export.h"
+
+namespace views {
+
+// Facilitates copying mus content window properties to mash frame root windows.
+class VIEWS_MUS_EXPORT MusPropertyMirror {
+ public:
+  virtual ~MusPropertyMirror() {}
+
+  // Called when a property with the given |key| has changed for |window|.
+  virtual void MirrorPropertyFromWidgetWindowToRootWindow(aura::Window* window,

[sky, 2017/01/27 20:10:45]

I'm surprised you don't need to forward declare window.

You should also mention window is the window returned from
widget->GetNativeWindow(). And to make it super class what the expectation is, I
would have this take the rootwindow and only call this function if there is a
root window.

[msw, 2017/01/27 21:19:25]

Done (and added aura::Window fwd decl).

+                                                          const void* key) = 0;
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_MUS_MUS_PROPERTY_MIRROR_H_