Explicit container priority

athena/screen/public/screen_manager.h

Index: athena/screen/public/screen_manager.h
diff --git a/athena/screen/public/screen_manager.h b/athena/screen/public/screen_manager.h
index 622f0479242de2859ee2f3d52f2a9979aa9c7d78..9e873061d354d15815392a2dbd6b9c95d1090cd1 100644
--- a/athena/screen/public/screen_manager.h
+++ b/athena/screen/public/screen_manager.h
@@ -29,11 +29,14 @@ namespace athena {
 class ATHENA_EXPORT ScreenManager {
  public:
   struct ContainerParams {
-    ContainerParams(const std::string& name);
+    ContainerParams(const std::string& name, int z_order_priority);
     std::string name;
 
     // True if the container can activate its child window.
     bool can_activate_children;
+
+    // Defines the z_order priority of the container.
+    int z_order_priority;
   };
 
   // Creates, returns and deletes the singleton object of the ScreenManager