Use JavaRef in JNI generator sample.

base/android/jni_generator/sample_for_tests.cc

 // Copyright (c) 2012 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 <iostream>
 
 #include "base/android/jni_generator/sample_for_tests.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
@@ skipping 99 matching lines @@
 int main() {
   // On a regular application, you'd call AttachCurrentThread(). This sample is
   // not yet linking with all the libraries.
   JNIEnv* env = /* AttachCurrentThread() */ NULL;
 
   // This is how you call a java static method from C++.
   bool foo = base::android::Java_SampleForTests_staticJavaMethod(env);
 
   // This is how you call a java method from C++. Note that you must have
   // obtained the jobject somehow.
-  jobject my_java_object = NULL;
+  ScopedJavaLocalRef<jobject> my_java_object;
   int bar = base::android::Java_SampleForTests_javaMethod(
       env, my_java_object, 1, 2);
 
   std::cout << foo << bar;
 
   for (int i = 0; i < 10; ++i) {
     // Creates a "struct" that will then be used by the java side.
     ScopedJavaLocalRef<jobject> struct_a =
         base::android::Java_InnerStructA_create(
             env, 0, 1, ConvertUTF8ToJavaString(env, "test"));
     base::android::Java_SampleForTests_addStructA(env, my_java_object,
                                                   struct_a);
   }
   base::android::Java_SampleForTests_iterateAndDoSomething(env, my_java_object);
   base::android::Java_SampleForTests_packagePrivateJavaMethod(env,
                                                               my_java_object);
   base::android::Java_SampleForTests_methodThatThrowsException(env,
                                                                my_java_object);
   base::android::Java_SampleForTests_javaMethodWithAnnotatedParam(
       env, my_java_object, 42);
   return 0;
 }