Cleanup ash shelf accessor functions.

ash/shelf/shelf_layout_manager.cc

Index: ash/shelf/shelf_layout_manager.cc
diff --git a/ash/shelf/shelf_layout_manager.cc b/ash/shelf/shelf_layout_manager.cc
index 110f38cfbb4badfc2f7e988323cd03562d1d5d87..c2e65a5a7ddf17b3916c6df84df506426c3c7c0d 100644
--- a/ash/shelf/shelf_layout_manager.cc
+++ b/ash/shelf/shelf_layout_manager.cc
@@ -544,12 +544,6 @@ void ShelfLayoutManager::SetChromeVoxPanelHeight(int height) {
   LayoutShelf();
 }
 
-// static
-ShelfLayoutManager* ShelfLayoutManager::ForShelf(aura::Window* window) {
-  ShelfWidget* shelf = RootWindowController::ForShelf(window)->shelf();
-  return shelf ? shelf->shelf_layout_manager() : NULL;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // ShelfLayoutManager, private: