This allows better code sharing in crashpad_handler’s main(). It doesn’t
look like much of an improvement now, but a separate change will cause
the Mac ExceptionHandlerServer() to be constructed with an argument. It
will be beneficial for Mac and Windows to be able to share the Run()
call.
R=scottmg@chromium.org
Review URL: https://codereview.chromium.org/1402333004 .