Reinstate a call to UsabilityStudyLogUtils#writeChar()

The usability study mode has been broken.

bug: 10251399
Change-Id: Iaa301241f102f412fa073f0d8b897a4c8b265a9c
diff --git a/java/src/com/android/inputmethod/latin/utils/UserLogRingCharBuffer.java b/java/src/com/android/inputmethod/latin/utils/UserLogRingCharBuffer.java
index 161386e..a75d353 100644
--- a/java/src/com/android/inputmethod/latin/utils/UserLogRingCharBuffer.java
+++ b/java/src/com/android/inputmethod/latin/utils/UserLogRingCharBuffer.java
@@ -19,6 +19,7 @@
 import android.inputmethodservice.InputMethodService;
 
 import com.android.inputmethod.annotations.UsedForTesting;
+import com.android.inputmethod.latin.LatinImeLogger;
 import com.android.inputmethod.latin.settings.Settings;
 
 public final class UserLogRingCharBuffer {
@@ -64,6 +65,9 @@
         if (!mEnabled) {
             return;
         }
+        if (LatinImeLogger.sUsabilityStudy) {
+            UsabilityStudyLogUtils.getInstance().writeChar(c, x, y);
+        }
         mCharBuf[mEnd] = c;
         mXBuf[mEnd] = x;
         mYBuf[mEnd] = y;