views: Make view::Views::GetPreferredSize() const.

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_
 
 #include "ash/ash_export.h"
 #include "ash/shelf/background_animator.h"
 #include "ash/shelf/shelf_types.h"
@@ skipping 23 matching lines @@
   class TrayContainer : public views::View {
    public:
     explicit TrayContainer(ShelfAlignment alignment);
     virtual ~TrayContainer() {}
 
     void SetAlignment(ShelfAlignment alignment);
 
     void set_size(const gfx::Size& size) { size_ = size; }
 
     // views::View:
-    virtual gfx::Size GetPreferredSize() OVERRIDE;
+    virtual gfx::Size GetPreferredSize() const OVERRIDE;
 
    protected:
     // views::View:
     virtual void ChildPreferredSizeChanged(views::View* child) OVERRIDE;
     virtual void ChildVisibilityChanged(View* child) OVERRIDE;
     virtual void ViewHierarchyChanged(
         const ViewHierarchyChangedDetails& details) OVERRIDE;
 
    private:
     void UpdateLayout();
@@ skipping 132 matching lines @@
 
   scoped_ptr<TrayWidgetObserver> widget_observer_;
   scoped_ptr<TrayEventFilter> tray_event_filter_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayBackgroundView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_BACKGROUND_VIEW_H_