base::mac::IsOSSierra() -> base::mac::IsOS10_12(), etc.

ui/views/controls/menu/menu_config_mac.mm

 // Copyright 2014 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.
 
 #include "ui/views/controls/menu/menu_config.h"
 
 #import <AppKit/AppKit.h>
 
 #include "base/mac/mac_util.h"
 
@@ skipping 13 matching lines @@
   item_top_margin = item_no_icon_top_margin = 1;
   item_bottom_margin = item_no_icon_bottom_margin = 1;
   item_left_margin = 2;
   arrow_to_edge_padding = 13;
   icon_to_label_padding = 4;
   check_width = 19;
   check_height = 11;
   separator_height = 13;
   separator_upper_height = 7;
   separator_lower_height = 6;
-  separator_thickness = base::mac::IsOSMavericks()
-                            ? kMenuSeparatorHeightMavericks
-                            : kMenuSeparatorHeight;
+  separator_thickness = base::mac::IsOS10_9() ? kMenuSeparatorHeightMavericks
+                                              : kMenuSeparatorHeight;
   align_arrow_and_shortcut = true;
   icons_in_label = true;
   check_selected_combobox_item = true;
   corner_radius = 5;
   use_outer_border = false;
 }
 
 }  // namespace views