button up vs cross the line

button up

verb
  • to conclude; to finalize; to put the finishing touches (on) 

  • To fasten with a button or buttons. 

  • To fasten all the buttons on a coat, or similar item of clothing, to keep warm. 

  • To seal off (a military vehicle or facility). 

cross the line

verb
  • To achieve completion of something. 

  • To finish a race. 

  • To overstep a boundary, rule, or limit; to go too far or do something unacceptable. 

  • To cross the equator, as a vessel at sea. 

  • To film from the opposite side of an imaginary axis on set in order to view the actors from the opposite direction. 

How often have the words button up and cross the line occurred in a corpus of books? (source: Google Ngram Viewer )