I have both of these, and also the 1930 and 1940 Censuses.
I have not been able to find him as a child in the census. His death certificate names his father as John, but mother is unknown. I do not find a California census with John Leyva as father, with John Leyva as a son. There are census records with Francisco and Antonio as the fathers, and sons John. But neither of these can be identified as John Robert Leyva. I am not convinced that the father’s name in the death certificate is correct, as the informant did not know the mother’s name. Also, the birthdate on the draft registration, which would have been provided by John Robert Leyva, differs by 10 years from that on the death certificate. I would give more credence to the draft registration than the death certificate.
The informant on the death certificate is Bob Leyva. I think this is actually Belvin Leyva, John Robert Leyva’s son, who went by Bob.
I have not yet found an obituary.