[Sync] Update SyncBackendHost to forward ClearServerData to SyncManager

chrome/browser/sync/glue/sync_backend_host_impl.h

Index: chrome/browser/sync/glue/sync_backend_host_impl.h
diff --git a/chrome/browser/sync/glue/sync_backend_host_impl.h b/chrome/browser/sync/glue/sync_backend_host_impl.h
index 5820b79efd922ecd7ecd723989de403f9b56c7b3..ff27d563cae34d5bb2651dc410e92caa461a924b 100644
--- a/chrome/browser/sync/glue/sync_backend_host_impl.h
+++ b/chrome/browser/sync/glue/sync_backend_host_impl.h
@@ -135,6 +135,8 @@ class SyncBackendHostImpl
                           ScopedVector<base::ListValue>)> type) override;
   base::MessageLoop* GetSyncLoopForTesting() override;
   void RefreshTypesForTest(syncer::ModelTypeSet types) override;
+  void ClearServerData(
+      const syncer::SyncManager::ClearServerDataCallback& callback) override;
 
  protected:
   // The types and functions below are protected so that test
@@ -301,6 +303,9 @@ class SyncBackendHostImpl
       const syncer::ObjectIdInvalidationMap& invalidation_map) override;
   std::string GetOwnerName() const override;
 
+  void ClearServerDataDoneOnFrontendLoop(
+      const syncer::SyncManager::ClearServerDataCallback& frontend_callback);
+
   content::NotificationRegistrar notification_registrar_;
 
   // A reference to the MessageLoop used to construct |this|, so we know how