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

ui/views/layout/box_layout.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 UI_VIEWS_LAYOUT_BOX_LAYOUT_H_
 #define UI_VIEWS_LAYOUT_BOX_LAYOUT_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/gfx/insets.h"
@@ skipping 28 matching lines @@
             int inside_border_vertical_spacing,
             int between_child_spacing);
   virtual ~BoxLayout();
 
   void set_spread_blank_space(bool spread) {
     spread_blank_space_ = spread;
   }
 
   // Overridden from views::LayoutManager:
   virtual void Layout(View* host) OVERRIDE;
-  virtual gfx::Size GetPreferredSize(View* host) OVERRIDE;
-  virtual int GetPreferredHeightForWidth(View* host, int width) OVERRIDE;
+  virtual gfx::Size GetPreferredSize(const View* host) const OVERRIDE;
+  virtual int GetPreferredHeightForWidth(const View* host,
+                                         int width) const OVERRIDE;
 
  private:
   // The preferred size for the dialog given the width of the child area.
-  gfx::Size GetPreferredSizeForChildWidth(View* host, int child_area_width);
+  gfx::Size GetPreferredSizeForChildWidth(const View* host,
+                                          int child_area_width) const;
 
   // The amount of space the layout requires in addition to any space for the
   // child views.
-  gfx::Size NonChildSize(View* host);
+  gfx::Size NonChildSize(const View* host) const;
 
   const Orientation orientation_;
 
   // Spacing between child views and host view border.
   gfx::Insets inside_border_insets_;
 
   // Spacing to put in between child views.
   const int between_child_spacing_;
 
   // Whether the available extra space should be distributed among the child
   // views.
   bool spread_blank_space_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BoxLayout);
 };
 
 } // namespace views
 
 #endif  // UI_VIEWS_LAYOUT_BOX_LAYOUT_H_