I had the first interview with Facebook's London office for Android Software Engineer position.
After introduction, interviewer asked following two questions related to Android:

1- What is onStop method, when is it called?
2- What is dp unit and why would you use it?

After this, the first algorithm questions was following:
https://leetcode.com/problems/buildings-with-an-ocean-view/

That was easy and I've solved in a timely manner.

Second question was about a MxN matrix, reaching from left-top of the matrix to right-bottom.
I don't remember every detail of this one but I will add the link here ones I found on LeetCode.

The interviewer was quite unfriednly and didn't really give any hint. I was very interactive and talked through entire interview, asked the interviewer each time what he thinks before I start coding.

Hope this helps someone.