Remove header dependencies from sequence_checker.h to sequenced_worker_pool.h

components/policy/core/common/cloud/device_management_service.h

 // Copyright (c) 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.
 
 #ifndef COMPONENTS_POLICY_CORE_COMMON_CLOUD_DEVICE_MANAGEMENT_SERVICE_H_
 #define COMPONENTS_POLICY_CORE_COMMON_CLOUD_DEVICE_MANAGEMENT_SERVICE_H_
 
 #include <stdint.h>
 
 #include <deque>
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string_split.h"
 #include "base/threading/thread_checker.h"
 #include "components/policy/core/common/cloud/cloud_policy_constants.h"
 #include "components/policy/policy_export.h"
 #include "components/policy/proto/device_management_backend.pb.h"
 #include "net/url_request/url_fetcher_delegate.h"
 
+namespace base {
+class SequencedTaskRunner;
+}
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace policy {
 
 class DeviceManagementRequestJobImpl;
 class DeviceManagementService;
 
@@ skipping 179 matching lines @@
 
   // Used to create tasks which run delayed on the UI thread.
   base::WeakPtrFactory<DeviceManagementService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceManagementService);
 };
 
 }  // namespace policy
 
 #endif  // COMPONENTS_POLICY_CORE_COMMON_CLOUD_DEVICE_MANAGEMENT_SERVICE_H_