[Sync] Update SyncBackendHost to forward ClearServerData to SyncManager

sync/internal_api/sync_manager_impl.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 SYNC_INTERNAL_API_SYNC_MANAGER_H_
 #define SYNC_INTERNAL_API_SYNC_MANAGER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 91 matching lines @@
   ScopedVector<syncer::ProtocolEvent> GetBufferedProtocolEvents() override;
   scoped_ptr<base::ListValue> GetAllNodesForType(
       syncer::ModelType type) override;
   void RegisterDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) override;
   void UnregisterDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) override;
   bool HasDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) override;
   void RequestEmitDebugInfo() override;
+  void ClearServerData(const ClearServerDataCallback& callback) override;
 
   // SyncEncryptionHandler::Observer implementation.
   void OnPassphraseRequired(
       PassphraseRequiredReason reason,
       const sync_pb::EncryptedData& pending_keys) override;
   void OnPassphraseAccepted() override;
   void OnBootstrapTokenUpdated(const std::string& bootstrap_token,
                                BootstrapTokenType type) override;
   void OnEncryptedTypesChanged(ModelTypeSet encrypted_types,
                                bool encrypt_everything) override;
@@ skipping 218 matching lines @@
   scoped_ptr<SyncEncryptionHandlerImpl> sync_encryption_handler_;
 
   base::WeakPtrFactory<SyncManagerImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncManagerImpl);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_SYNC_MANAGER_H_