[Sync] Update SyncBackendHost to forward ClearServerData to SyncManager

chrome/browser/sync/glue/sync_backend_host_core.h

Index: chrome/browser/sync/glue/sync_backend_host_core.h
diff --git a/chrome/browser/sync/glue/sync_backend_host_core.h b/chrome/browser/sync/glue/sync_backend_host_core.h
index 111061a6e2fad678211d99ad94a35c876328d404..d3a4b5cf655666d169a05a45011ab79a2f540c82 100644
--- a/chrome/browser/sync/glue/sync_backend_host_core.h
+++ b/chrome/browser/sync/glue/sync_backend_host_core.h
@@ -242,6 +242,9 @@ class SyncBackendHostCore
   // application is backgrounded.
   void SaveChanges();
 
+  void DoClearServerData(
+      const syncer::SyncManager::ClearServerDataCallback& frontend_callback);
+
  private:
   friend class base::RefCountedThreadSafe<SyncBackendHostCore>;
   friend class SyncBackendHostForProfileSyncTest;
@@ -254,6 +257,8 @@ class SyncBackendHostCore
   // be run on; the host's |registrar_->sync_thread()|.
   void StartSavingChanges();
 
+  void ClearServerDataDone(const base::Closure& frontend_callback);
+
   // Name used for debugging.
   const std::string name_;