Now Playing: Sen. John McCain gives daughter Meghan McCain a special birthday gift

Now Playing: How Amazon is studying body sizes to help make clothes fit better

Now Playing: 'GMA' Deals and Steals on Wheels: Nashville

Now Playing: Ron Howard celebrates 'Star Wars Day' on 'GMA'

Now Playing: Charlize Theron opens up about 'Tully' live on 'GMA'

Now Playing: Taylor Swift rides 'cat-icorn' in new DirecTV ad

Now Playing: Meghan Markle's half-brother pens open letter to Harry

Now Playing: 4-year-old becomes 'real-life superhero' to his baby brothers

Now Playing: Could inexpensive chargers put your iPhone at risk?

Now Playing: New evidence could link alleged 'Golden State Killer' to crimes

Now Playing: High school student hospitalized after prom party hypnosis

Now Playing: Woman accused of kidnapping baby faces bio mom in court

Now Playing: White House faces questions of credibility

Now Playing: John McCain reads passionate excerpt from memoir

Now Playing: Cop caught on video kicking suspect in head

Now Playing: Investigators were tracking Michael Cohen's calls

Now Playing: Hawaii volcano eruption: What are warning signs?

Now Playing: Hawaii volcano eruption sends lava flowing through streets

Now Playing: Kids battling cancer get superhero and princess photo shoots

Now Playing: Dressing Room Reveal: Meet Victory Boyd