Before joining Android I spent 3 years working on Chrome for Android. My changes to Chromium are publicly available to anyone interested. I mostly worked on front-end features of Chrome, but I was also interested in keeping code clean and Chrome for Android as small as possible.
Over my time as a programmer and a geek I worked with a number of languages (Java, Python, C++, PHP, etc.). I think that every language has its own designated purpose, but currently I am a big fan of Kotlin.