Remove Unused AsTextButtonBorder RTTI helper.

ui/views/border.h

Index: ui/views/border.h
diff --git a/ui/views/border.h b/ui/views/border.h
index 2467939f19f5a6fcfa4e121a1fea0c645baab6aa..d2657c60c13c927348b373311c9ef03268dbac90 100644
--- a/ui/views/border.h
+++ b/ui/views/border.h
@@ -37,8 +37,6 @@ class View;
 //
 ////////////////////////////////////////////////////////////////////////////////
 
-class TextButtonBorder;
-
 class VIEWS_EXPORT Border {
  public:
   Border();
@@ -86,10 +84,6 @@ class VIEWS_EXPORT Border {
   // content laid out relative to these images.
   virtual gfx::Size GetMinimumSize() const = 0;
 
-  // Manual RTTI for text buttons.
-  virtual TextButtonBorder* AsTextButtonBorder();
-  virtual const TextButtonBorder* AsTextButtonBorder() const;
-
  private:
   DISALLOW_COPY_AND_ASSIGN(Border);
 };