Moves Shell::CreateShelf() to WmShell

ash/common/wm_root_window_controller.h

Index: ash/common/wm_root_window_controller.h
diff --git a/ash/common/wm_root_window_controller.h b/ash/common/wm_root_window_controller.h
index f052c1cc4c70909d7f9860568a4082dd98a1c6da..66384b8eb93c12cbb09bd59e711cc3cafc665924 100644
--- a/ash/common/wm_root_window_controller.h
+++ b/ash/common/wm_root_window_controller.h
@@ -94,6 +94,9 @@ class ASH_EXPORT WmRootWindowController {
 
   virtual WmShelf* GetShelf() = 0;
 
+  // Creates the shelf for this root window and notifies observers.
+  void CreateShelf();
+
   // Show shelf view if it was created hidden (before session has started).
   // TODO(jamescook): Eliminate this and handle show via Shelf.
   void ShowShelf();