jni_generator: Make all object-returning natives return ScopedJavaLocalRef.

sync/android/model_type_helper.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/android/model_type_helper.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "jni/ModelTypeHelper_jni.h"
 #include "sync/internal_api/public/base/model_type.h"
 
 namespace syncer {
 
-static jstring ModelTypeToNotificationType(JNIEnv* env,
-                                           jclass clazz,
-                                           jint model_type_int) {
+static ScopedJavaLocalRef<jstring>
+ModelTypeToNotificationType(JNIEnv* env, jclass clazz, jint model_type_int) {
   std::string model_type_string;
   ModelType model_type = static_cast<ModelType>(model_type_int);
   if (!RealModelTypeToNotificationType(model_type, &model_type_string)) {
     NOTREACHED() << "No string representation of model type " << model_type;
   }
-  return base::android::ConvertUTF8ToJavaString(env, model_type_string)
-      .Release();
+  return base::android::ConvertUTF8ToJavaString(env, model_type_string);
 }
 
 bool RegisterModelTypeHelperJni(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace syncer