Add a JNI to get the frequency

Bug: 4192129
Change-Id: I3f220f5a10114d4eb23956148076cf76220bda0f
diff --git a/native/jni/src/unigram_dictionary.h b/native/jni/src/unigram_dictionary.h
index b923351..b708940 100644
--- a/native/jni/src/unigram_dictionary.h
+++ b/native/jni/src/unigram_dictionary.h
@@ -72,7 +72,7 @@
 
     UnigramDictionary(const uint8_t* const streamStart, int typedLetterMultipler,
             int fullWordMultiplier, int maxWordLength, int maxWords, const unsigned int flags);
-    bool isValidWord(const int32_t* const inWord, const int length) const;
+    int getFrequency(const int32_t* const inWord, const int length) const;
     int getBigramPosition(int pos, unsigned short *word, int offset, int length) const;
     int getSuggestions(ProximityInfo *proximityInfo, WordsPriorityQueuePool *queuePool,
             Correction *correction, const int *xcoordinates, const int *ycoordinates,