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

ui/views/bubble/bubble_border.h

Index: ui/views/bubble/bubble_border.h
===================================================================
--- ui/views/bubble/bubble_border.h	(revision 236640)
+++ ui/views/bubble/bubble_border.h	(working copy)
@@ -162,8 +162,10 @@
   // Overridden from Border:
   virtual void Paint(const View& view, gfx::Canvas* canvas) OVERRIDE;
   virtual gfx::Insets GetInsets() const OVERRIDE;
+  virtual gfx::Size GetMinimumSize() const OVERRIDE;
 
  private:
+  gfx::Size GetSizeForContentsSize(const gfx::Size& contents_size) const;
   gfx::ImageSkia* GetArrowImage() const;
   gfx::Rect GetArrowRect(const gfx::Rect& bounds) const;
   void DrawArrow(gfx::Canvas* canvas, const gfx::Rect& arrow_bounds) const;