I received a reply from Eve today. Her aunt (either Alice or Sandra) told her that Baby Boy Warren is Earl Francis Warren. I had only a 1949 birth for him, so it makes sense. I took another look at the Minnesota Birth Index and found another Baby Boy Warren born to Lawrence L. Warren and Mamie H. Smith on 9 Nov 1948 in Hennepin County. This correlates to the Baby Boy Warren who, according to the Minnesota Death Index, died the same day in Hennepin County.
I didn’t find Earl Francis Warren listed in the birth index and Eve said her aunt didn’t know why he wasn’t named shortly after birth. Her aunt said that Earl was born in St. Paul [in a hospital] and the other children had been born at home. It’s possible that the birth was recorded before Elry and Dorothy had decided on a name. I imagine that in the case of a home birth, the birth might not be recorded for a few days, giving the parents more time to decide on a name.