From the CFP website (obviously there's more, but relevant to the current discussion):
The criteria to be provided to the selection committee must be aligned with the ideals of the commissioners, presidents, athletic directors and coaches to honor regular season success while at the same time providing enough flexibility and discretion to select a non-champion or independent under circumstances where that particular non-champion or independent is unequivocally one of the four best teams in the country.
When circumstances at the margins indicate that teams are comparable, then the following criteria must be considered:
- Championships won
- Strength of schedule
- Head-to-head competition (if it occurred)
- Comparative outcomes of common opponents (without incenting margin of victory
http://www.collegefootballplayoff.com/selection-committee-protocol