Add a functionality to clear and flush prediction dictionary

    public void unRegisterUpdateSession(PersonalizationDictionaryUpdateSession session) {

        mSessions.remove(session);

    }

    public void clearAndFlushDictionary() {

        // Clear the node structure on memory

        clearDictionary();

        mBigramListLock.lock();

        try {

            // Clear the bigram list on memory

            mBigramList.evictAll();

        } finally {

            mBigramListLock.unlock();

        }

        // Then flush the cleared state of the dictionary on disk.

        flushPendingWrites();

    }

}

        dictionary.unRegisterUpdateSession(this);

    }

    public void clearAndFlushPredictionDictionary(Context context) {

        final DynamicPredictionDictionaryBase dictionary = getPredictionDictionary();

        if (dictionary == null) {

            return;

        }

        dictionary.clearAndFlushDictionary();

    }

    public void closeSession(Context context) {

        unsetPredictionDictionary();