Delete IsAtLeastOS10_9() and IsAtMostOS10_9()

ui/native_theme/native_theme_mac.mm

Index: ui/native_theme/native_theme_mac.mm
diff --git a/ui/native_theme/native_theme_mac.mm b/ui/native_theme/native_theme_mac.mm
index 5f1f8d9d83cc11ef14e0c7e31ca0fec6b37b8563..36e04dacf781176e4350dd60e9fad8392798e0c5 100644
--- a/ui/native_theme/native_theme_mac.mm
+++ b/ui/native_theme/native_theme_mac.mm
@@ -181,8 +181,8 @@ SkColor NativeThemeMac::GetSystemColor(ColorId color_id) const {
     case kColorId_MenuBackgroundColor:
       return kMenuPopupBackgroundColor;
     case kColorId_MenuSeparatorColor:
-      return base::mac::IsOS10_9() ? kMenuSeparatorColorMavericks
-                                   : kMenuSeparatorColor;
+      return base::mac::IsAtLeastOS10_10() ? kMenuSeparatorColor
+                                           : kMenuSeparatorColorMavericks;
     case kColorId_MenuBorderColor:
       return kMenuBorderColor;
 
@@ -243,10 +243,10 @@ void NativeThemeMac::PaintMenuPopupBackground(
     const MenuBackgroundExtraParams& menu_background) const {
   SkPaint paint;
   paint.setAntiAlias(true);
-  if (base::mac::IsOS10_9())
-    paint.setColor(kMenuPopupBackgroundColorMavericks);
-  else
+  if (base::mac::IsAtLeastOS10_10())
     paint.setColor(kMenuPopupBackgroundColor);
+  else
+    paint.setColor(kMenuPopupBackgroundColorMavericks);
   const SkScalar radius = SkIntToScalar(menu_background.corner_radius);
   SkRect rect = gfx::RectToSkRect(gfx::Rect(size));
   canvas->drawRoundRect(rect, radius, radius, paint);