(Merge to M-51) Revise the shelf alignment locking mechanism.

ash/system/date/tray_date.cc

 // Copyright (c) 2012 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/date/tray_date.h"
 
+#include "ash/shelf/shelf_util.h"
 #include "ash/shell.h"
 #include "ash/system/date/date_default_view.h"
 #include "ash/system/date/date_view.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "ash/system/tray/tray_item_view.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/system/chromeos/system_clock_observer.h"
 #endif
@@ skipping 71 matching lines @@
 
 void TrayDate::DestroyDetailedView() {
 }
 
 void TrayDate::UpdateAfterLoginStatusChange(user::LoginStatus status) {
 }
 
 void TrayDate::UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) {
   if (time_tray_) {
     ClockLayout clock_layout =
-        alignment == SHELF_ALIGNMENT_BOTTOM ? HORIZONTAL_CLOCK : VERTICAL_CLOCK;
+        IsHorizontalAlignment(alignment) ? HORIZONTAL_CLOCK : VERTICAL_CLOCK;
     time_tray_->UpdateClockLayout(clock_layout);
   }
 }
 
 void TrayDate::OnDateFormatChanged() {
   if (time_tray_)
     time_tray_->UpdateTimeFormat();
   if (default_view_)
     default_view_->GetDateView()->UpdateTimeFormat();
 }
@@ skipping 13 matching lines @@
         can_set_time ? TrayDate::SET_SYSTEM_TIME : TrayDate::NONE);
   }
 }
 
 void TrayDate::Refresh() {
   if (time_tray_)
     time_tray_->UpdateText();
 }
 
 }  // namespace ash