[ObjC ARC] Converts components/sessions:unit_tests to ARC.

components/sessions/ios/ios_serialized_navigation_builder_unittest.mm

 // Copyright 2014 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 "components/sessions/ios/ios_serialized_navigation_builder.h"
 
 #include "components/sessions/core/serialized_navigation_entry.h"
 #include "components/sessions/core/serialized_navigation_entry_test_helper.h"
 #include "ios/web/public/favicon_status.h"
 #include "ios/web/public/navigation_item.h"
 #include "ios/web/public/referrer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace sessions {
 
 namespace {
 // Creates a NavigationItem from the test_data constants in
 // serialized_navigation_entry_test_helper.h.
 std::unique_ptr<web::NavigationItem> MakeNavigationItemForTest() {
   std::unique_ptr<web::NavigationItem> navigation_item(
       web::NavigationItem::Create());
   navigation_item->SetReferrer(web::Referrer(
       test_data::kReferrerURL,
@@ skipping 73 matching lines @@
   EXPECT_EQ(old_navigation_item->GetTitle(),
             new_navigation_item->GetTitle());
   EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
                   new_navigation_item->GetTransitionType(),
                   ui::PAGE_TRANSITION_RELOAD));
   EXPECT_EQ(old_navigation_item->GetTimestamp(),
             new_navigation_item->GetTimestamp());
 }
 
 }  // namespace sessions