Use PrevWordsInfo for get/add/remove n-gram(bigram) entry.

Bug: 14119293
Bug: 14425059
Bug: 15102610
Change-Id: Ib482390f8d15b37d44a1a54e8c243a9eaec3f815
15 files changed
tree: 7f21c8bf2fe1a67c4fa7e71d58a0708623304f8e
  1. dictionaries/
  2. java/
  3. native/
  4. tests/
  5. tools/
  6. Android.mk
  7. CleanSpec.mk