Remove unused ash::SHELF_ALIGNMENT_TOP

ash/system/web_notification/web_notification_tray.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/web_notification/web_notification_tray.h"
 
 #include "ash/ash_switches.h"
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
@@ skipping 208 matching lines @@
           true);
 
   int max_height = 0;
   aura::Window* status_area_window = status_area_widget()->GetNativeView();
   switch (GetShelfLayoutManager()->GetAlignment()) {
     case SHELF_ALIGNMENT_BOTTOM: {
       gfx::Rect shelf_bounds = GetShelfLayoutManager()->GetIdealBounds();
       max_height = shelf_bounds.y();
       break;
     }
-    case SHELF_ALIGNMENT_TOP: {
-      aura::Window* root = status_area_window->GetRootWindow();
-      max_height =
-          root->bounds().height() - status_area_window->bounds().height();
-      break;
-    }
     case SHELF_ALIGNMENT_LEFT:
     case SHELF_ALIGNMENT_RIGHT: {
       // Assume that the bottom line of the status area widget and the bubble
       // are aligned.
       max_height = status_area_window->GetBoundsInRootWindow().bottom();
       break;
     }
-    default:
-      NOTREACHED();
   }
 
   message_center_bubble->SetMaxHeight(std::max(0,
                                                max_height - kTraySpacing));
   if (show_settings)
     message_center_bubble->SetSettingsVisible();
   message_center_bubble_.reset(
       new WebNotificationBubbleWrapper(this, message_center_bubble));
 
   status_area_widget()->SetHideSystemNotifications(true);
@@ skipping 242 matching lines @@
 
 message_center::MessageCenterBubble*
 WebNotificationTray::GetMessageCenterBubbleForTest() {
   if (!message_center_bubble())
     return NULL;
   return static_cast<message_center::MessageCenterBubble*>(
       message_center_bubble()->bubble());
 }
 
 }  // namespace ash