Fix mash shelf alignment change layout regression.

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 a24e6a0ea35f7176561fcd2553c7763861d1d3dc..f541ab5ae98933db032e98963f098a87f15d1b40 100644
--- a/ash/shelf/shelf_layout_manager.cc
+++ b/ash/shelf/shelf_layout_manager.cc
@@ -521,6 +521,11 @@ void ShelfLayoutManager::OnLockStateChanged(bool locked) {
   UpdateShelfVisibilityAfterLoginUIChange();
 }
 
+void ShelfLayoutManager::OnShelfAlignmentChanged(aura::Window* root_window) {
+  if (aura::GetMusWindow(shelf_->GetNativeWindow()))

[James Cook, 2016/05/09 19:39:36]

I think ash::Shell::GetInstance()->in_mus() would be clearer, since it doesn't
conflate the mus-check with the window-existance-check.

[msw, 2016/05/09 19:50:00]

Done.

+    LayoutShelf();
+}
+
 void ShelfLayoutManager::OnShelfAutoHideBehaviorChanged(
     aura::Window* root_window) {
   UpdateVisibilityState();