Reland: mash: Fix MusPropertyMirrorAsh for owned properties; add test.

ash/wm/window_properties.h

Index: ash/wm/window_properties.h
diff --git a/ash/wm/window_properties.h b/ash/wm/window_properties.h
index c0c3d035f8882af76d13587c6783ddd484f21d2c..561f18be2213dd9e49de1c90ce498f6d12e3f8b2 100644
--- a/ash/wm/window_properties.h
+++ b/ash/wm/window_properties.h
@@ -47,9 +47,6 @@ enum class WidgetCreationType {
 // bounds outside of its root window is set.
 ASH_EXPORT extern const aura::WindowProperty<bool>* const kLockedToRootKey;
 
-// If true (and the window is a panel), it's attached to its shelf item.
-ASH_EXPORT extern const aura::WindowProperty<bool>* const kPanelAttachedKey;
-
 // A property key which stores the bounds to restore a window to. These take
 // preference over the current bounds/state. This is used by e.g. the always
 // maximized mode window manager.
@@ -65,9 +62,6 @@ ASH_EXPORT extern const aura::WindowProperty<ui::WindowShowState>* const
 // A property key to store the id for a window's shelf item.
 ASH_EXPORT extern const aura::WindowProperty<ShelfID>* const kShelfIDKey;
 
-// A property key to store the type of a window's shelf item.
-ASH_EXPORT extern const aura::WindowProperty<int32_t>* const kShelfItemTypeKey;
-
 // Containers with this property (true) are aligned with physical pixel
 // boundary.
 extern const aura::WindowProperty<bool>* const kSnapChildrenToPixelBoundary;