Properly set ShelfAlignment during login

ash/shelf/shelf_layout_manager.h

Index: ash/shelf/shelf_layout_manager.h
diff --git a/ash/shelf/shelf_layout_manager.h b/ash/shelf/shelf_layout_manager.h
index 7e0118a79f0dd43414e7692d28abd18edfe2ec74..590ca547b5b8bc90dc13ad239eec99786692a1e9 100644
--- a/ash/shelf/shelf_layout_manager.h
+++ b/ash/shelf/shelf_layout_manager.h
@@ -326,6 +326,9 @@ class ASH_EXPORT ShelfLayoutManager
   // Called when the LoginUI changes from visible to invisible.
   void UpdateShelfVisibilityAfterLoginUIChange();
 
+  // Returns true when |alignment_| should not be used for layout.
+  bool ShouldOverrideAlignment() const;
+
   // The RootWindow is cached so that we don't invoke Shell::GetInstance() from
   // our destructor. We avoid that as at the time we're deleted Shell is being
   // deleted too.