Forgot to check in a file.

layout/base/public/nsISelfScrollingFrame.h

@@ -17,6 +17,7 @@ class nsISelfScrollingFrame : public nsISupports {
 
   NS_IMETHOD ScrollByLines(nsIPresContext* aPresContext, PRInt32 lines)=0;
 
+  NS_IMETHOD CollapseScrollbar(nsIPresContext* aPresContext, PRBool aHide) = 0;
 };
 
 #endif /* _nsISelfScrollingFrame_h */