How to kill google photos process? My Google Photos service on osx is hung.  There's no obvious process to kill and try to restart.  

I'm on OSX 10.11.2
Open the Activity Monitor app (found in the /Applications/Utilities folder) and select the process from the list. Click the stop process button at the top left of the Activity Monitor window. If the process is a background process, you will have to select the memory tab to see the list of background processes.