Internally they profile power usage, or at least power usage regressions. I recall watching a Chromium issue where new code was reverted out because it caused

Internally they profile power usage, or at least power usage regressions. I recall watching a Chromium issue where new code was reverted out because it caused an unacceptably large increase in power usage. I think the power graph was published in the issue, and perhaps the profiling was on Android, but I'm uncertain of exact details.