Use the correct launcher assets for shelf alignment.

ash/launcher/launcher_alignment_menu.cc

Index: ash/launcher/launcher_alignment_menu.cc
diff --git a/ash/launcher/launcher_alignment_menu.cc b/ash/launcher/launcher_alignment_menu.cc
index 304c239c08c3d5b4996bdf0f27f39a5a92581d9e..54e12d57ddd834bc4ab228d088891eff1726d0bc 100644
--- a/ash/launcher/launcher_alignment_menu.cc
+++ b/ash/launcher/launcher_alignment_menu.cc
@@ -5,8 +5,10 @@
 #include "ash/launcher/launcher_alignment_menu.h"
 
 #include "ash/shell.h"
+#include "ash/wm/shelf_layout_manager.h"
 #include "ash/wm/shelf_types.h"
 #include "grit/ash_strings.h"
+#include "ui/aura/root_window.h"
 #include "ui/base/l10n/l10n_util.h"
 
 namespace ash {
@@ -33,19 +35,11 @@ LauncherAlignmentMenu::~LauncherAlignmentMenu() {
 }
 
 bool LauncherAlignmentMenu::IsCommandIdChecked(int command_id) const {
-  switch (command_id) {
-    case MENU_ALIGN_LEFT:
-      return Shell::GetInstance()->GetShelfAlignment(root_window_) ==
-          SHELF_ALIGNMENT_LEFT;
-    case MENU_ALIGN_BOTTOM:
-      return Shell::GetInstance()->GetShelfAlignment(root_window_) ==
-          SHELF_ALIGNMENT_BOTTOM;
-    case MENU_ALIGN_RIGHT:
-      return Shell::GetInstance()->GetShelfAlignment(root_window_) ==
-          SHELF_ALIGNMENT_RIGHT;
-    default:
-      return false;
-  }
+  return internal::ShelfLayoutManager::ForLauncher(root_window_)->
+      SelectValueForShelfAlignment(
+          MENU_ALIGN_BOTTOM == command_id,
+          MENU_ALIGN_LEFT == command_id,
+          MENU_ALIGN_RIGHT == command_id);
 }
 
 bool LauncherAlignmentMenu::IsCommandIdEnabled(int command_id) const {