BoxLayout: Added set_collapse_when_hidden(), like views::Label.

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 <map>
 
 #include "base/basictypes.h"
@@ skipping 63 matching lines @@
   }
 
   void set_inside_border_insets(const gfx::Insets& insets) {
     inside_border_insets_ = insets;
   }
 
   void set_minimum_cross_axis_size(int size) {
     minimum_cross_axis_size_ = size;
   }
 
+  // Sets whether the preferred size is empty when the host is not visible.
+  void set_collapse_when_hidden(bool value) { collapse_when_hidden_ = value; }
+
   // Sets the flex weight for the given |view|. Using the preferred size as
   // the basis, free space along the main axis is distributed to views in the
   // ratio of their flex weights. Similarly, if the views will overflow the
   // parent, space is subtracted in these ratios.
   //
   // A flex of 0 means this view is not resized. Flex values must not be
   // negative.
   void SetFlexForView(const View* view, int flex);
 
   // Clears the flex for the given |view|, causing it to use the default
@@ skipping 64 matching lines @@
 
   // A map of views to their flex weights.
   std::map<const View*, int> flex_map_;
 
   // The flex weight for views if none is set. Defaults to 0.
   int default_flex_;
 
   // The minimum cross axis size for the layout.
   int minimum_cross_axis_size_;
 
+  // Whether to collapse the host when it's not visible.
+  bool collapse_when_hidden_;
+
   // The view that this BoxLayout is managing the layout for.
   views::View* host_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BoxLayout);
 };
 
 } // namespace views
 
 #endif  // UI_VIEWS_LAYOUT_BOX_LAYOUT_H_