[Sync] Replace ClearServerDataCallback with Closure.

components/sync/engine_impl/sync_manager_impl.cc

Index: components/sync/engine_impl/sync_manager_impl.cc
diff --git a/components/sync/engine_impl/sync_manager_impl.cc b/components/sync/engine_impl/sync_manager_impl.cc
index b4f52a506c6a00575786a543a03e49887acf923b..87724d4de44c1ab56d915af57070933276147d69 100644
--- a/components/sync/engine_impl/sync_manager_impl.cc
+++ b/components/sync/engine_impl/sync_manager_impl.cc
@@ -995,7 +995,7 @@ void SyncManagerImpl::RequestEmitDebugInfo() {
   model_type_registry_->RequestEmitDebugInfo();
 }
 
-void SyncManagerImpl::ClearServerData(const ClearServerDataCallback& callback) {
+void SyncManagerImpl::ClearServerData(const base::Closure& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
   scheduler_->Start(SyncScheduler::CLEAR_SERVER_DATA_MODE, base::Time());
   ClearParams params(callback);