void didUpdateScrollBehavior(double newScrollOffset)

Update any in-progress scrolling physics to account for new scroll behavior.

The scrolling physics depends on the scroll behavior. When changing the scrolling behavior, call this function to update any in-progress scrolling physics to account for the new scroll behavior. This function preserves the current velocity when updating the physics.

If there are no in-progress scrolling physics, this function scrolls to the given offset instead.

Source 

void didUpdateScrollBehavior(double newScrollOffset) {
  _setStateMaybeDuringBuild(() {
    _contentExtent = scrollBehavior.contentExtent;
    _containerExtent = scrollBehavior.containerExtent;
  });

  // This does not call setState, because if anything below actually
  // changes our build, it will itself independently trigger a frame.
  assert(_controller.isAnimating || _simulation == null);
  if (_numberOfInProgressScrolls > 0) {
    if (_simulation != null) {
      double dx = _simulation.dx(_controller.lastElapsedDuration.inMicroseconds / Duration.MICROSECONDS_PER_SECOND);
      _startToEndAnimation(dx); // dx - logical pixels / second
    }
    return;
  }
  scrollTo(newScrollOffset);
}