components: Cleanup class/struct fwd declarations

components/sync/driver/glue/sync_backend_host.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_
 #define COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/threading/thread.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/base/weak_handle.h"
 #include "components/sync/driver/backend_data_type_configurer.h"
 #include "components/sync/engine/configure_reason.h"
 #include "components/sync/engine/cycle/sync_cycle_snapshot.h"
 #include "components/sync/engine/shutdown_reason.h"
 #include "components/sync/engine/sync_manager.h"
 #include "components/sync/engine/sync_manager_factory.h"
 
 class GURL;
 
-namespace base {
-class MessageLoop;
-}  // namespace base
-
 namespace syncer {
 
 class CancelationSignal;
-class ChangeProcessor;
 class HttpPostProviderFactory;
 class SyncFrontend;
 class SyncManagerFactory;
 class UnrecoverableErrorHandler;
 
 // An API to "host" the top level SyncAPI element.
 //
 // This class handles dispatch of potentially blocking calls to appropriate
 // threads and ensures that the SyncFrontend is only accessed on the UI loop.
 class SyncBackendHost : public BackendDataTypeConfigurer {
@@ skipping 159 matching lines @@
   // See SyncManager::OnCookieJarChanged.
   virtual void OnCookieJarChanged(bool account_mismatch, bool empty_jar) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_