views: remove PlatformStyle::CreateLabelButtonBorder

ui/views/style/platform_style.h

Index: ui/views/style/platform_style.h
diff --git a/ui/views/style/platform_style.h b/ui/views/style/platform_style.h
index bc9eab35332e1e8bba1cdbbb0fb294d051be8170..8405cb2009a6d2284b297e80343f7efd728c9cde 100644
--- a/ui/views/style/platform_style.h
+++ b/ui/views/style/platform_style.h
@@ -19,7 +19,6 @@ class Border;
 class FocusableBorder;
 class Label;
 class LabelButton;
-class LabelButtonBorder;
 class ScrollBar;
 
 // Cross-platform API for providing platform-specific styling for toolkit-views.
@@ -70,11 +69,6 @@ class VIEWS_EXPORT PlatformStyle {
   static std::unique_ptr<Background> CreateComboboxBackground(
       int shoulder_width);
 
-  // Creates the default label button border for the given |style|. Used when a
-  // custom default border is not provided for a particular LabelButton class.
-  static std::unique_ptr<LabelButtonBorder> CreateLabelButtonBorder(
-      Button::ButtonStyle style);
-
   // Creates the default scrollbar for the given orientation.
   static std::unique_ptr<ScrollBar> CreateScrollBar(bool is_horizontal);