I prepared extensively.

The interview process:

• Two phone screens
• In-depth technical interview on-site (equivalent to five one-on-one oral exams)
• Six phone calls with team leaders to find a good fit

I do not feel comfortable sharing this because I signed a document stating I would not share it. This should be respected.

One other thing that helped a lot was reaching out to friends at Google for mock interviews. Engineers are recommended to do an interview a week, and this was very helpful.