As JT says the words net and gross are not usually applied to the take-off distances.
Gross performance is the average performance of a group of aeroplanes being tested according to an approved method. If you work to gross performance standards you have a 50:50 probability of achieving them. Net is the gross performance reduced so that the probability of an aircraft not achieving the standard is remote, defined in turn as 1:100 000 to 1:10 000 000.
I would say the distance to the 35ft screen height is gross in the engine out case, there being no margins applied other than the improbability of a failure, i.e. after the engine failure net = gross and you have a 50:50 chance of making the screen height if you go, and that the distance to 35ft in the all engine case is a net distance because of the 1.15 safety factor. i.e. net = gross x 1.15 and you have only a remote probability of not making 35ft on a normal all engines take-off.