am 770626e0: merge in master-release history after reset to...

am 770626e0: merge in master-release history after reset to dc1e70b3

* commit '770626e0':
  Revert "Use PrevWordsInfo for get/add/remove n-gram(bigram) entry."
  Fix a NPE in DistracterFilter.isDistracterToWordsInDictionaries()
  Fix NPE
  Fix: NPE after onDestroy().
  Fix a null object reference crash on Emoji Palette
  Fix an NPE.
  Revert "Fix a race condition."