[ObjC ARC] Converts ios/web:ios_web_public_unittests to ARC.

ios/web/public/serializable_user_data_manager_unittest.mm

 // Copyright 2017 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.
 
 #import "ios/web/public/serializable_user_data_manager.h"
 
-#import "base/mac/scoped_nsobject.h"
 #import "ios/web/public/test/fakes/test_web_state.h"
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // User Data and Key to use for tests.
 NSString* const kTestUserData = @"TestUserData";
 NSString* const kTestUserDataKey = @"TestUserDataKey";
 }  // namespace
 
 class SerializableUserDataManagerTest : public PlatformTest {
  protected:
   // Convenience getter for the user data manager.
   web::SerializableUserDataManager* manager() {
@@ skipping 11 matching lines @@
 }
 
 // Tests that SerializableUserData can successfully encode and decode.
 TEST_F(SerializableUserDataManagerTest, EncodeDecode) {
   // Create a SerializableUserData instance for the test data.
   manager()->AddSerializableData(kTestUserData, kTestUserDataKey);
   std::unique_ptr<web::SerializableUserData> user_data =
       manager()->CreateSerializableUserData();
 
   // Archive the serializable user data.
-  base::scoped_nsobject<NSMutableData> data([[NSMutableData alloc] init]);
-  base::scoped_nsobject<NSKeyedArchiver> archiver(
-      [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]);
+  NSMutableData* data = [[NSMutableData alloc] init];
+  NSKeyedArchiver* archiver =
+      [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
   user_data->Encode(archiver);
   [archiver finishEncoding];
 
   // Create a new SerializableUserData by unarchiving.
-  base::scoped_nsobject<NSKeyedUnarchiver> unarchiver(
-      [[NSKeyedUnarchiver alloc] initForReadingWithData:data]);
+  NSKeyedUnarchiver* unarchiver =
+      [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
   std::unique_ptr<web::SerializableUserData> decoded_data =
       web::SerializableUserData::Create();
   decoded_data->Decode(unarchiver);
 
   // Add the decoded user data to a new WebState and verify its contents.
   web::TestWebState decoded_web_state;
   web::SerializableUserDataManager* decoded_manager =
       web::SerializableUserDataManager::FromWebState(&decoded_web_state);
   decoded_manager->AddSerializableUserData(decoded_data.get());
   id decoded_value =
       decoded_manager->GetValueForSerializationKey(kTestUserDataKey);
   EXPECT_NSEQ(decoded_value, kTestUserData);
 }