Prepare status area to support multiple trays.

ash/system/tray/tray_background_view.h

 // 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.
 
 #ifndef ASH_SYSTEM_TRAY_TRAY_BACKGROUND_VIEW_H_
 #define ASH_SYSTEM_TRAY_TRAY_BACKGROUND_VIEW_H_
 #pragma once
 
 #include "ash/ash_export.h"
 #include "ash/launcher/background_animator.h"
 #include "ash/system/tray/tray_views.h"
+#include "ash/wm/shelf_auto_hide_behavior.h"
 
 namespace ash {
 namespace internal {
 
 class TrayBackground;
 
 // Base class for children of StatusAreaWidget: SystemTray, WebNotificationTray.
 // This class handles setting and animating the background when the Launcher
 // his shown/hidden. It also inherits from ActionableView so that the tray
 // items can override PerformAction when clicked on.
 
 class ASH_EXPORT TrayBackgroundView : public internal::ActionableView,
                                       public BackgroundAnimatorDelegate {
  public:
   TrayBackgroundView();
   virtual ~TrayBackgroundView();
 
   // Overridden from views::View.
   virtual void OnMouseEntered(const views::MouseEvent& event) OVERRIDE;
   virtual void OnMouseExited(const views::MouseEvent& event) OVERRIDE;
 
   // Overridden from internal::ActionableView.
   virtual bool PerformAction(const views::Event& event) OVERRIDE;
 
   // Overridden from internal::BackgroundAnimatorDelegate.
   virtual void UpdateBackground(int alpha) OVERRIDE;
 
+  // Called whenever the shelf alignment changes.
+  virtual void SetShelfAlignment(ShelfAlignment alignment);
+
   // Sets |contents| as a child and sets its background to |background_|.
   void SetContents(views::View* contents);
 
   // Sets whether the tray paints a background. Default is true, but is set to
   // false if a window overlaps the shelf.
   void SetPaintsBackground(
       bool value,
       internal::BackgroundAnimator::ChangeType change_type);
 
+  ShelfAlignment shelf_alignment() const { return shelf_alignment_; }
+
  private:
+  // Shelf alignment.
+  ShelfAlignment shelf_alignment_;
+
   // Owned by the view passed to SetContents().
   internal::TrayBackground* background_;
 
   internal::BackgroundAnimator hide_background_animator_;
   internal::BackgroundAnimator hover_background_animator_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayBackgroundView);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_BACKGROUND_VIEW_H_