Update shelf spacing in Chrome OS according to the MD specs

ash/system/web_notification/ash_popup_alignment_delegate.cc

 // Copyright 2014 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/ash_popup_alignment_delegate.h"
 
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/shelf_types.h"
 #include "ash/common/wm_lookup.h"
 #include "ash/common/wm_shell.h"
@@ skipping 44 matching lines @@
     UpdateWorkArea();
 }
 
 void AshPopupAlignmentDelegate::SetSystemTrayHeight(int height) {
   system_tray_height_ = height;
 
   // If the shelf is shown during auto-hide state, the distance from the edge
   // should be reduced by the height of shelf's shown height.
   if (shelf_->visibility_state() == SHELF_AUTO_HIDE &&
       shelf_->auto_hide_state() == SHELF_AUTO_HIDE_SHOWN) {
-    system_tray_height_ -= kShelfSize - ShelfLayoutManager::kAutoHideSize;
+    system_tray_height_ -= GetShelfConstant(SHELF_SIZE) - kShelfAutoHideSize;
   }
 
   if (system_tray_height_ > 0)
     system_tray_height_ += message_center::kMarginBetweenItems;
   else
     system_tray_height_ = 0;
 
   DoUpdateIfPossible();
 }
 
@@ skipping 67 matching lines @@
     const display::Display& old_display) {}
 
 void AshPopupAlignmentDelegate::OnDisplayMetricsChanged(
     const display::Display& display,
     uint32_t metrics) {
   if (GetCurrentDisplay().id() == display.id())
     UpdateWorkArea();
 }
 
 }  // namespace ash