Comment 3 for bug 1388070

Proximity sensor is an API that developers are welcome to use (please refer to the Screen blanking policy: https://docs.google.com/document/d/1RBoVknCLZ4GQ8E_iVftd3i_KmdxI5d6JrBt7i5EDZO0/edit?usp=sharing) However, we won't use it for the default behaviour of the Clock app. It's a feature that requires discovery and understanding of usage for the 'standard' user.