Use PrevWordsInfo instead of String in Java side.

java/src/com/android/inputmethod/latin/BinaryDictionary.java

java/src/com/android/inputmethod/latin/Dictionary.java

...c/com/android/inputmethod/latin/DictionaryCollection.java

...id/inputmethod/latin/DictionaryFacilitatorForSuggest.java

...android/inputmethod/latin/ExpandableBinaryDictionary.java

java/src/com/android/inputmethod/latin/LatinIME.java

java/src/com/android/inputmethod/latin/PrevWordsInfo.java

...m/android/inputmethod/latin/ReadOnlyBinaryDictionary.java

java/src/com/android/inputmethod/latin/Suggest.java

java/src/com/android/inputmethod/latin/WordComposer.java

...utmethod/latin/spellcheck/AndroidSpellCheckerSession.java

...latin/spellcheck/AndroidWordLevelSpellCheckerSession.java

.../android/inputmethod/latin/spellcheck/DictionaryPool.java

...ellcheck/SynchronouslyLoadedContactsBinaryDictionary.java

...n/spellcheck/SynchronouslyLoadedUserBinaryDictionary.java

...com/android/inputmethod/latin/utils/DistracterFilter.java

...m/android/inputmethod/latin/utils/LanguageModelParam.java

...c/com/android/inputmethod/latin/DistracterFilterTest.java

.../src/com/android/inputmethod/latin/WordComposerTests.java

tools/dicttool/Android.mk