Revert of [Sync] IWYU cleanup.

chrome/browser/sync/test/integration/multi_client_status_change_checker.cc

 // 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 "chrome/browser/sync/test/integration/multi_client_status_change_checker.h"
 
 #include "base/logging.h"
+#include "base/scoped_observer.h"
 #include "components/browser_sync/profile_sync_service.h"
 
 MultiClientStatusChangeChecker::MultiClientStatusChangeChecker(
     std::vector<browser_sync::ProfileSyncService*> services)
     : services_(services), scoped_observer_(this) {
   for (browser_sync::ProfileSyncService* service : services) {
     scoped_observer_.Add(service);
   }
 }
 
 MultiClientStatusChangeChecker::~MultiClientStatusChangeChecker() {}
 
 void MultiClientStatusChangeChecker::OnStateChanged() {
   CheckExitCondition();
 }