Updates shadow when active window changes

mash/wm/property_util.h

Index: mash/wm/property_util.h
diff --git a/mash/wm/property_util.h b/mash/wm/property_util.h
index 104e870b0e8d1ff18828ecd018b6311bd42b436c..4e7616b243057e3245e008197fdaf307046499a5 100644
--- a/mash/wm/property_util.h
+++ b/mash/wm/property_util.h
@@ -21,6 +21,8 @@ class Window;
 namespace mash {
 namespace wm {
 
+class Shadow;
+
 // Utility functions to read values from properties & convert them to the
 // appropriate types.
 
@@ -39,6 +41,9 @@ mus::mojom::ResizeBehavior GetResizeBehavior(const mus::Window* window);
 void SetRestoreBounds(mus::Window* window, const gfx::Rect& bounds);
 gfx::Rect GetRestoreBounds(const mus::Window* window);
 
+void SetShadow(mus::Window* window, Shadow* shadow);
+Shadow* GetShadow(mus::Window* window);
+
 }  // namespace wm
 }  // namespace mash