On Windows it is quite easy to end up with a file which mostly has the correct \n line endings but in some places has \r\n line endings. VS will helpfully warn you about this, but usually only after your change has been submitted. I have fixed these errors twice in the last few months, most recently crrev.com/c/846542.

There are some source files that are entirely \r\n so I think that this presubmit should just warn about inconsistencies.

I'm assigning this to myself but if anybody else wants it just set it to Started/youralias@