Revise the shelf alignment locking mechanism.

ash/system/cast/tray_cast.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/cast/tray_cast.h"
 
 #include "ash/session/session_state_delegate.h"
 #include "ash/shelf/shelf_types.h"
+#include "ash/shelf/shelf_util.h"
 #include "ash/shell.h"
 #include "ash/system/chromeos/screen_security/screen_tray_item.h"
 #include "ash/system/tray/fixed_sized_image_view.h"
 #include "ash/system/tray/fixed_sized_scroll_view.h"
 #include "ash/system/tray/hover_highlight_view.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "ash/system/tray/throbber_view.h"
 #include "ash/system/tray/tray_constants.h"
@@ skipping 331 matching lines @@
   image_view()->SetImage(ui::ResourceBundle::GetSharedInstance()
                              .GetImageNamed(IDR_AURA_UBER_TRAY_SCREENSHARE)
                              .ToImageSkia());
 }
 
 CastTrayView::~CastTrayView() {
 }
 
 void CastTrayView::UpdateAlignment(ShelfAlignment alignment) {
   // Center the item dependent on the orientation of the shelf.
-  views::BoxLayout::Orientation layout = views::BoxLayout::kHorizontal;
-  switch (alignment) {
-    case ash::SHELF_ALIGNMENT_BOTTOM:
-      layout = views::BoxLayout::kHorizontal;
-      break;
-    case ash::SHELF_ALIGNMENT_LEFT:
-    case ash::SHELF_ALIGNMENT_RIGHT:
-      layout = views::BoxLayout::kVertical;
-      break;
-  }
+  views::BoxLayout::Orientation layout = IsHorizontalAlignment(alignment)
+                                             ? views::BoxLayout::kVertical
+                                             : views::BoxLayout::kHorizontal;
   SetLayoutManager(new views::BoxLayout(layout, 0, 0, 0));
   Layout();
 }
 
 // This view displays a list of cast receivers that can be clicked on and casted
 // to. It is activated by clicking on the chevron inside of
 // |CastSelectDefaultView|.
 class CastDetailedView : public TrayDetailsView, public ViewClickListener {
  public:
   CastDetailedView(SystemTrayItem* owner,
@@ skipping 298 matching lines @@
   is_casting_ = started;
   UpdatePrimaryView();
 }
 
 void TrayCast::UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) {
   if (tray_)
     tray_->UpdateAlignment(alignment);
 }
 
 }  // namespace ash