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

ui/views/controls/tree/tree_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 UI_VIEWS_CONTROLS_TREE_TREE_VIEW_VIEWS_H_
 #define UI_VIEWS_CONTROLS_TREE_TREE_VIEW_VIEWS_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 103 matching lines @@
   // Returns the node for the specified row, or NULL for an invalid row index.
   ui::TreeModelNode* GetNodeForRow(int row);
 
   // Maps a node to a row, returns -1 if node is not valid.
   int GetRowForNode(ui::TreeModelNode* node);
 
   views::Textfield* editor() { return editor_; }
 
   // View overrides:
   virtual void Layout() OVERRIDE;
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
+  virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual bool AcceleratorPressed(const ui::Accelerator& accelerator) OVERRIDE;
   virtual bool OnMousePressed(const ui::MouseEvent& event) OVERRIDE;
   virtual ui::TextInputClient* GetTextInputClient() OVERRIDE;
   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
   virtual void ShowContextMenu(const gfx::Point& p,
                                ui::MenuSourceType source_type) OVERRIDE;
   virtual void GetAccessibleState(ui::AXViewState* state) OVERRIDE;
   virtual const char* GetClassName() const OVERRIDE;
 
   // TreeModelObserver overrides:
@@ skipping 253 matching lines @@
   int text_offset_;
 
   scoped_ptr<PrefixSelector> selector_;
 
   DISALLOW_COPY_AND_ASSIGN(TreeView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_TREE_TREE_VIEW_VIEWS_H_