Revert of [Sync] IWYU cleanup.

components/sync/engine_impl/sync_manager_impl_unittest.cc

 // Copyright 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 "components/sync/engine_impl/sync_manager_impl.h"
 
 #include <cstddef>
+#include <memory>
 #include <utility>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/format_macros.h"
 #include "base/location.h"
 #include "base/metrics/field_trial.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 3517 matching lines @@
 // SyncManagerInitInvalidStorageTest::GetFactory will return
 // DirectoryBackingStore that ensures that SyncManagerImpl::OpenDirectory fails.
 // SyncManagerImpl initialization is done in SyncManagerTest::SetUp. This test's
 // task is to ensure that SyncManagerImpl reported initialization failure in
 // OnInitializationComplete callback.
 TEST_F(SyncManagerInitInvalidStorageTest, FailToOpenDatabase) {
   EXPECT_FALSE(initialization_succeeded_);
 }
 
 }  // namespace syncer