Contacts dictionary rebuilds only when contact names have changed.

Bug: 6396600
Change-Id: Iad693ec4bab6351793d624e5c5b0a9f5c12a60e3
diff --git a/native/jni/src/dictionary.cpp b/native/jni/src/dictionary.cpp
index 9dc2072..8ea7c49 100644
--- a/native/jni/src/dictionary.cpp
+++ b/native/jni/src/dictionary.cpp
@@ -58,4 +58,9 @@
     return mUnigramDictionary->isValidWord(word, length);
 }
 
+bool Dictionary::isValidBigram(const int32_t *word1, int length1, const int32_t *word2,
+        int length2) {
+    return mBigramDictionary->isValidBigram(word1, length1, word2, length2);
+}
+
 } // namespace latinime