views: remove PlatformStyle::CreateLabelButtonBorder

ui/views/style/platform_style_mac.mm

Index: ui/views/style/platform_style_mac.mm
diff --git a/ui/views/style/platform_style_mac.mm b/ui/views/style/platform_style_mac.mm
index 8cc98004f6ce3dcd5019c7379b611e0cc968b32d..ef80dea70aea9295ef03ad441bb95f466a894cf2 100644
--- a/ui/views/style/platform_style_mac.mm
+++ b/ui/views/style/platform_style_mac.mm
@@ -61,15 +61,6 @@
 }
 
 // static
-std::unique_ptr<LabelButtonBorder> PlatformStyle::CreateLabelButtonBorder(
-    Button::ButtonStyle style) {
-  if (style == Button::STYLE_BUTTON)
-    return base::MakeUnique<DialogButtonBorderMac>();
-
-  return base::MakeUnique<LabelButtonAssetBorder>(style);
-}
-
-// static
 std::unique_ptr<ScrollBar> PlatformStyle::CreateScrollBar(bool is_horizontal) {
   return base::MakeUnique<CocoaScrollBar>(is_horizontal);
 }