It's confusing that seekTo(player, windowIndex, positionMs) does
clamping, because it only makes sense if windowIndex is the current
window.
Note: This doesn't actually fix anything (other than code clarity).
In cases where we were passing other windowIndices, we always
passed 0 as the position and so the clamping logic wouldn't have
had any effect.
PiperOrigin-RevId: 272857104
