Merge changes I94a64865,I62725bfe

* changes:
  Refactor step3: const unigram_dictionary
  refactor native step 2
tree: 5b9f432740d68f7ee82ffe7806ca7799bf0354a4
  1. dictionaries/
  2. java/
  3. native/
  4. tests/
  5. tools/
  6. Android.mk
  7. CleanSpec.mk