[Sync] Update SyncBackendHost to forward ClearServerData to SyncManager

chrome/browser/sync/glue/sync_backend_host.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 CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 204 matching lines @@
   virtual void EnableDirectoryTypeDebugInfoForwarding() = 0;
 
   // Disables the sending of directory type debug counters.
   virtual void DisableDirectoryTypeDebugInfoForwarding() = 0;
 
   virtual base::MessageLoop* GetSyncLoopForTesting() = 0;
 
   // Triggers sync cycle to update |types|.
   virtual void RefreshTypesForTest(syncer::ModelTypeSet types) = 0;
 
+  // See SyncManager::ClearServerData.
+  virtual void ClearServerData(
+      const syncer::SyncManager::ClearServerDataCallback& callback) = 0;
+
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_