Add palette tray to ash.

ash/common/system/tray/tray_bubble_wrapper.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_COMMON_SYSTEM_TRAY_TRAY_BUBBLE_WRAPPER_H_
 #define ASH_COMMON_SYSTEM_TRAY_TRAY_BUBBLE_WRAPPER_H_
 
 #include "base/macros.h"
 #include "ui/views/widget/widget_observer.h"
 
@@ skipping 13 matching lines @@
                     views::TrayBubbleView* bubble_view);
   ~TrayBubbleWrapper() override;
 
   // views::WidgetObserver overrides:
   void OnWidgetDestroying(views::Widget* widget) override;
   void OnWidgetBoundsChanged(views::Widget* widget,
                              const gfx::Rect& new_bounds) override;
 
   const TrayBackgroundView* tray() const { return tray_; }
   TrayBackgroundView* tray() { return tray_; }
+  views::TrayBubbleView* bubble_view() { return bubble_view_; }
   const views::TrayBubbleView* bubble_view() const { return bubble_view_; }
   const views::Widget* bubble_widget() const { return bubble_widget_; }
 
  private:
   TrayBackgroundView* tray_;
   views::TrayBubbleView* bubble_view_;  // unowned
   views::Widget* bubble_widget_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayBubbleWrapper);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_BUBBLE_WRAPPER_H_