The chords are really easy and sound pretty good. Us Justin Bieber fans should be 
happy!Its the same through the whole song so im just gonna do the chorus

Capo on 1st fret

  C
  Baby, baby, baby nooo

  Am    
  My baby, baby, baby noo

  F
  My baby, baby, baby nooo

  G
  I thought youd always be mine mine