Add StatsUtils method for handling subtype change.

Change-Id: I0f334ab5e6f5aa41ad780641276dc3d2aa232f48

java-overridable/src/com/android/inputmethod/latin/utils/StatsUtils.java

@@ -16,6 +16,8 @@
 
 package com.android.inputmethod.latin.utils;
 
+import android.view.inputmethod.InputMethodSubtype;
+
 import com.android.inputmethod.latin.RichInputMethodManager;
 import com.android.inputmethod.latin.SuggestedWords;
 import com.android.inputmethod.latin.settings.SettingsValues;
@@ -86,4 +88,8 @@ public final class StatsUtils {
 
     public static void onInvalidWordIdentification(final String invalidWord) {
     }
+
+    public static void onSubtypeChanged(final InputMethodSubtype oldSubtype,
+            final InputMethodSubtype newSubtype) {
+    }
 }

java/src/com/android/inputmethod/latin/LatinIME.java

@@ -793,6 +793,8 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
     public void onCurrentInputMethodSubtypeChanged(final InputMethodSubtype subtype) {
         // Note that the calling sequence of onCreate() and onCurrentInputMethodSubtypeChanged()
         // is not guaranteed. It may even be called at the same time on a different thread.
+        InputMethodSubtype oldSubtype = mRichImm.getCurrentSubtype().getRawSubtype();
+        StatsUtils.onSubtypeChanged(oldSubtype, subtype);
         mRichImm.onSubtypeChanged(subtype);
         mInputLogic.onSubtypeChanged(SubtypeLocaleUtils.getCombiningRulesExtraValue(subtype),
                 mSettings.getCurrent());