Support storing the VisibilityClient on windows other than the RootWindow. What this means is you c…

ui/aura/client/visibility_client.h

Index: ui/aura/client/visibility_client.h
===================================================================
--- ui/aura/client/visibility_client.h	(revision 192570)
+++ ui/aura/client/visibility_client.h	(working copy)
@@ -8,7 +8,6 @@
 #include "ui/aura/aura_export.h"
 
 namespace aura {
-class RootWindow;
 class Window;
 namespace client {
 
@@ -25,11 +24,13 @@
   virtual ~VisibilityClient() {}
 };
 
-// Sets/Gets the VisibilityClient on the RootWindow.
-AURA_EXPORT void SetVisibilityClient(RootWindow* root_window,
-                                     VisibilityClient* client);
-AURA_EXPORT VisibilityClient* GetVisibilityClient(RootWindow* root_window);
+// Sets the VisibilityClient on the Window.
+AURA_EXPORT void SetVisibilityClient(Window* window, VisibilityClient* client);
 
+// Gets the VisibilityClient for the window. This will crawl up |window|'s
+// hierarchy until it finds one.
+AURA_EXPORT VisibilityClient* GetVisibilityClient(Window* window);
+
 }  // namespace clients
 }  // namespace aura