Refactors DockedWindowLayoutManager in terms of ash/wm/common

ash/mus/shelf_delegate_mus.cc

Index: ash/mus/shelf_delegate_mus.cc
diff --git a/ash/mus/shelf_delegate_mus.cc b/ash/mus/shelf_delegate_mus.cc
index fff6233af5a72cab81ff26ceea0d57fe4320ff17..e701e369e44856ac1fd37d685ce2a01b0e1afc41 100644
--- a/ash/mus/shelf_delegate_mus.cc
+++ b/ash/mus/shelf_delegate_mus.cc
@@ -258,7 +258,7 @@ void ShelfDelegateMus::AddObserver(
 }
 
 void ShelfDelegateMus::SetAlignment(mash::shelf::mojom::Alignment alignment) {
-  ShelfAlignment value = static_cast<ShelfAlignment>(alignment);
+  wm::ShelfAlignment value = static_cast<wm::ShelfAlignment>(alignment);
   Shell::GetInstance()->SetShelfAlignment(value, Shell::GetPrimaryRootWindow());
 }