Generally getting to senior is much more straightforward than moving past that. In a Google-style system, senior is the terminal level, which everyone is expected to reach. So there should be clear guidelines and a lot of examples of others who have been promoted there.

I can't speak for every company, but generally for a senior promotion you just need to prove that you are a competent developer and can be trusted to deliver medium-sized projects (e.g., 3 developers for a quarter) from design to release without much or any oversight.

If you're not getting those opportunities, you need to talk to your manager about that.

That seems to be mostly it, though I've found there's a little bit more to it. Namely, not presenting your raw unfiltered thoughts and opinions as much but presenting them through more of a "party line" filter.

The Managers Path is a good book. It gives guidance through all career stages.