The API is no longer being updated here until further notice.

Updates the scroll frame's scroll child rectangle.

ScrollFrame:UpdateScrollChildRect()

Details

• You were required to call this when you changed the contents of your ScrollFrame prior to patch 2.3. You no longer need to call it now. If a child frame, texture or fontstring has changed, the scroll parent will automatically recalculate it's scroll rect and dispatch events appropriately.
• You do need to call it before calling your own :SetVerticalScroll() to flush pending updates (for instance after you inserted text in the scrolling edit box)