Fix unit tests by adding @UsedForTesting.

Change-Id: I62ec07210817295f59a174383ee4b33cc4fc2ca6
diff --git a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
index 918b610..6199c7d 100644
--- a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
@@ -362,6 +362,7 @@
     /**
      * Dynamically remove the n-gram entry in the dictionary.
      */
+    @UsedForTesting
     public void removeNgramDynamically(final PrevWordsInfo prevWordsInfo, final String word) {
         reloadDictionaryIfRequired();
         asyncExecuteTaskWithWriteLock(new Runnable() {