jni_generator: Make all object-returning natives return ScopedJavaLocalRef.

chrome/browser/android/web_contents_factory.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 "chrome/browser/android/web_contents_factory.h"
 
 #include "base/android/jni_android.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "content/public/browser/android/content_view_core.h"
 #include "content/public/browser/web_contents.h"
 #include "jni/WebContentsFactory_jni.h"
 
-static jobject CreateWebContents(
-    JNIEnv* env, jclass clazz, jboolean incognito, jboolean initially_hidden) {
+static ScopedJavaLocalRef<jobject> CreateWebContents(
+    JNIEnv* env,
+    jclass clazz,
+    jboolean incognito,
+    jboolean initially_hidden) {
   Profile* profile = g_browser_process->profile_manager()->GetLastUsedProfile();
   if (incognito)
     profile = profile->GetOffTheRecordProfile();
 
   content::WebContents::CreateParams params(profile);
   params.initially_hidden = static_cast<bool>(initially_hidden);
-  return content::WebContents::Create(params)->GetJavaWebContents().Release();
+  return content::WebContents::Create(params)->GetJavaWebContents();
 }
 
 bool RegisterWebContentsFactory(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }