I can't tell from the pedigree if your mare has a chance of being homozygous gray or not (both her parents would have to have been gray for this to be a possibility). If she is homozygous gray, then the foal will definitely gray out. Otherwise, there's a 50/50 chance of it inheriting the gray gene.
As for the base color, the sire is EE aa, and if the mare was born black we'll assume she's Ee aa (although she might also be EE aa). This gives a 75% chance of a black foal, and 25% chance of chestnut. If the mare is actually EE aa, there's a 100% chance of a black foal.