[ObjC ARC] Converts ios/chrome/browser/ui/bookmarks:bookmarks_arc to ARC.

ios/chrome/browser/ui/bookmarks/bookmark_utils_ios_unittest.mm

 // 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 <memory>
 #include <vector>
 
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "ios/chrome/browser/experimental_flags.h"
 #include "ios/chrome/browser/ui/bookmarks/bookmark_ios_unittest.h"
 #import "ios/chrome/browser/ui/bookmarks/bookmark_menu_item.h"
 #import "ios/chrome/browser/ui/bookmarks/bookmark_utils_ios.h"
 #include "testing/gtest_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using bookmarks::BookmarkNode;
 
 namespace {
 
 using bookmark_utils_ios::NodesSection;
 
 class BookmarkIOSUtilsUnitTest : public BookmarkIOSUnitTest {
  protected:
   base::Time timeFromEpoch(int days, int hours) {
     return base::Time::UnixEpoch() + base::TimeDelta::FromDays(days) +
@@ skipping 359 matching lines @@
   vector1.push_back(bookmark1);
   vector2.insert(vector2.begin(), bookmark1);
   missingNodesIndices =
       bookmark_utils_ios::MissingNodesIndices(vector1, vector2);
   EXPECT_EQ(2u, missingNodesIndices.size());
   EXPECT_EQ(2u, missingNodesIndices[0]);
   EXPECT_EQ(3u, missingNodesIndices[1]);
 }
 
 }  // namespace