ash: Explicitly teach various components about ShelfLayoutManager.

ash/system/tray/tray_background_view.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/tray/tray_background_view.h"
 
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_widget.h"
@@ skipping 372 matching lines @@
     bool value, BackgroundAnimatorChangeType change_type) {
   hide_background_animator_.SetPaintsBackground(value, change_type);
 }
 
 void TrayBackgroundView::SetContentsBackground() {
   background_ = new TrayBackground(this);
   tray_container_->set_background(background_);
 }
 
 ShelfLayoutManager* TrayBackgroundView::GetShelfLayoutManager() {
-  return ShelfLayoutManager::ForShelf(GetWidget()->GetNativeView());
+  return status_area_widget()->shelf_widget()->shelf_layout_manager();
 }
 
 void TrayBackgroundView::SetShelfAlignment(ShelfAlignment alignment) {
   shelf_alignment_ = alignment;
   SetTrayBorder();
   tray_container_->SetAlignment(alignment);
 }
 
 void TrayBackgroundView::SetTrayBorder() {
   views::View* parent = status_area_widget_->status_area_widget_delegate();
@@ skipping 187 matching lines @@
     background_->set_alpha(kTrayBackgroundAlpha);
   SchedulePaint();
 }
 
 void TrayBackgroundView::UpdateBubbleViewArrow(
     views::TrayBubbleView* bubble_view) {
   // Nothing to do here.
 }
 
 }  // namespace ash