ash: Convert ShelfDelegate to use WmShelf* instead of Shelf*

ash/root_window_controller.cc

Index: ash/root_window_controller.cc
diff --git a/ash/root_window_controller.cc b/ash/root_window_controller.cc
index e061b02bafd9e8298246cecb006914ba6d00b594..7b32c256fab9e14aec8357d20d002d62c1af319b 100644
--- a/ash/root_window_controller.cc
+++ b/ash/root_window_controller.cc
@@ -478,7 +478,7 @@ void RootWindowController::CreateShelf() {
   // Must be initialized before the delegate is notified because the delegate
   // may try to access the WmShelf.
   wm_shelf_aura_->SetShelf(shelf_.get());
-  WmShell::Get()->shelf_delegate()->OnShelfCreated(shelf_.get());
+  WmShell::Get()->shelf_delegate()->OnShelfCreated(wm_shelf_aura_.get());
 
   if (panel_layout_manager_)
     panel_layout_manager_->SetShelf(wm_shelf_aura_.get());