jni_generator: Make all object-returning natives return ScopedJavaLocalRef.

content/browser/android/tracing_controller_android.cc

 // Copyright 2013 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 "content/browser/android/tracing_controller_android.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
@@ skipping 84 matching lines @@
        ++it) {
     category_list.AppendString(*it);
   }
   std::string received_category_list;
   base::JSONWriter::Write(category_list, &received_category_list);
 
   // This log is required by adb_profile_chrome.py.
   LOG(WARNING) << "{\"traceCategoriesList\": " << received_category_list << "}";
 }
 
-static jstring GetDefaultCategories(JNIEnv* env, jobject obj) {
+static ScopedJavaLocalRef<jstring> GetDefaultCategories(JNIEnv* env,
+                                                        jobject obj) {
   base::trace_event::TraceConfig trace_config;
   return base::android::ConvertUTF8ToJavaString(
-             env,
-             trace_config.ToCategoryFilterString())
-      .Release();
+      env, trace_config.ToCategoryFilterString());
 }
 
 bool RegisterTracingControllerAndroid(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content