Merge "[Rlog50] capture bigrams properly even with deletions"

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

...rc/com/android/inputmethod/latin/RichInputConnection.java

.../src/com/android/inputmethod/research/FixedLogBuffer.java

java/src/com/android/inputmethod/research/LogBuffer.java

java/src/com/android/inputmethod/research/LogUnit.java

java/src/com/android/inputmethod/research/MainLogBuffer.java

.../src/com/android/inputmethod/research/ResearchLogger.java