When the camera manager calls stop on a pipeline, it is expected that the pipeline handler guarantees all requests are returned back to the application before the camera has stopped. Ensure that this guarantee is met by providing an accessor on the pipeline handler to validate that all pending requests are removed. Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>