Like her granddaughter would decades later, Dolores began acting in films when she was about six years old. She and her sister Helene came from a long line of theatricals, and like nearly every other early film goddess, was practically born on stage. She appeared in many early Vitagraph shorts and on Broadway, transitioning seemingly effortlessly from child to adult roles. Eventually, she was dubbed the "Goddess of the Silent Screen", marrying Barrymore, one of the great stars of the age.
Unfortunately, though Barrymore is easily one of the best actors I've ever seen, he was also a jealous, abusive drunk. Costello divorced him in 1935, and married her obstetrician. In the 1930s, the harsh makeup in use began destroying her porcelain skin (Max Factor! How dare you!). It got so bad, it couldn't be hidden by makeup or cinematography, so her career ended. One of her last roles was in Orson Welles's The Magnificent Ambersons. She lived most of the rest of her life in near seclusion on an avocado farm, dying in 1979.
I don't know if Drew ever met her grandmother, but judging by Dolores's seclusion, and the chaos surrounding the grownups in young Drew's life, I somehow doubt it. Looking at lots of photographs of Dolores all at once, her resemblance to her granddaughter is strong.
On YouTube, you can watch all of The Sea Beast, an extremely loose adaptation of Moby Dick and the film on which Barrymore and Costello met. Putting Spiderman to shame, six extras drowned during filming and Costello contracted pneumonia. See the first part below: