\version "2.10.10"

harmony = \context ChordNames {
  \chordmode {
    c1 |
    c1 |
  }
}
slashes = {
  \override NoteHead #'style = #'slash
  b'1 |
  b'1 |
}
 
<< 
  \harmony
  \new Staff {
    \slashes
  }
>>