diff --git a/atom/browser/ui/cocoa/touch_bar_forward_declarations.h b/atom/browser/ui/cocoa/touch_bar_forward_declarations.h
index 6fe7c820a1c..062723bca67 100644
--- a/atom/browser/ui/cocoa/touch_bar_forward_declarations.h
+++ b/atom/browser/ui/cocoa/touch_bar_forward_declarations.h
@@ -15,7 +15,7 @@
 
 @class NSTouchBar, NSTouchBarItem;
 @class NSScrubber, NSScrubberItemView, NSScrubberArrangedView, NSScrubberTextItemView, NSScrubberImageItemView, NSScrubberSelectionStyle;
-@protocol NSTouchBarDelegate, NSScrubberDelegate, NSScrubberDataSource;
+@protocol NSTouchBarDelegate, NSScrubberDelegate, NSScrubberDataSource, NSScrubberFlowLayoutDelegate, NSScrubberFlowLayout;
 
 typedef float NSTouchBarItemPriority;
 static const NSTouchBarItemPriority NSTouchBarItemPriorityHigh = 1000;
@@ -149,6 +149,9 @@ static const NSTouchBarItemIdentifier NSTouchBarItemIdentifierOtherItemsProxy =
 
 @end
 
+@interface NSScrubberFlowLayout: NSObject
+@end
+
 @interface NSScrubberSelectionStyle : NSObject<NSCoding>
 
 @property(class, strong, readonly) NSScrubberSelectionStyle* outlineOverlayStyle;
@@ -229,6 +232,12 @@ static const NSTouchBarItemIdentifier NSTouchBarItemIdentifierOtherItemsProxy =
 
 @end
 
+@protocol NSScrubberFlowLayoutDelegate<NSObject>
+
+- (NSSize)scrubber:(NSScrubber *)scrubber layout:(NSScrubberFlowLayout *)layout sizeForItemAtIndex:(NSInteger)itemIndex;
+
+@end
+
 #pragma clang assume_nonnull end
 
 #elif MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_12_1