Add GetMinimumSize() for Borders, and make LabelButton auto-size to at least as

ui/views/shadow_border.h

 // Copyright 2013 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_SHADOW_BORDER_H_
 #define UI_VIEWS_SHADOW_BORDER_H_
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/views/border.h"
 #include "ui/views/views_export.h"
 
 namespace views {
 
 // Creates a css box-shadow like border which fades into SK_ColorTRANSPARENT.
 class VIEWS_EXPORT ShadowBorder : public views::Border {
  public:
   ShadowBorder(int blur,
                SkColor color,
                int vertical_offset,
                int horizontal_offset);
   virtual ~ShadowBorder();
 
  protected:
   // Overridden from views::Border:
   virtual void Paint(const views::View& view, gfx::Canvas* canvas) OVERRIDE;
   virtual gfx::Insets GetInsets() const OVERRIDE;
+  virtual gfx::Size GetMinimumSize() const OVERRIDE;
 
  private:
   // Blur amount of the shadow in pixels. For details on how blur is defined see
   // comments for blur_ in class ShadowValue.
   const int blur_;
 
   // Shadow color.
   const SkColor color_;
 
   // Number of pixels to shift shadow to bottom.
   const int vertical_offset_;
 
   // Number of pixels to shift shadow to right.
   const int horizontal_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(ShadowBorder);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_SHADOW_BORDER_H_