Fix NPE

Change-Id: Ic438704af64e8ebcecba13dbc0f3e72b14ac6f4f
diff --git a/java/src/com/android/inputmethod/latin/LatinImeLogger.java b/java/src/com/android/inputmethod/latin/LatinImeLogger.java
index c03d1a7..c03e7d0 100644
--- a/java/src/com/android/inputmethod/latin/LatinImeLogger.java
+++ b/java/src/com/android/inputmethod/latin/LatinImeLogger.java
@@ -284,10 +284,8 @@
     public static void logOnAutoSuggestion(String before, String after) {
         if (sLogEnabled) {
             String[] strings = new String[] {before, after};
-            synchronized (sLastAutoSuggestBefore) {
+            synchronized (LatinImeLogger.class) {
                 sLastAutoSuggestBefore = before;
-            }
-            synchronized (sLastAutoSuggestAfter) {
                 sLastAutoSuggestAfter = after;
             }
             sLatinImeLogger.sendLogToDropBox(ID_AUTOSUGGESTIONCANCELED, strings);