Avoid useless SYNC_CYCLE_CONTINUATION sync cycle

chrome/browser/sync/engine/process_updates_command.cc

Index: chrome/browser/sync/engine/process_updates_command.cc
diff --git a/chrome/browser/sync/engine/process_updates_command.cc b/chrome/browser/sync/engine/process_updates_command.cc
index 47812502e02d3821bda3d5085cb633b8222153da..05e1ad05b429488109dfcd7f9e602be1fe9bb021 100644
--- a/chrome/browser/sync/engine/process_updates_command.cc
+++ b/chrome/browser/sync/engine/process_updates_command.cc
@@ -32,18 +32,19 @@ std::set<ModelSafeGroup> ProcessUpdatesCommand::GetGroupsToChange(
   return session.GetEnabledGroupsWithVerifiedUpdates();
 }
 
-void ProcessUpdatesCommand::ModelChangingExecuteImpl(SyncSession* session) {
+SyncerError ProcessUpdatesCommand::ModelChangingExecuteImpl(
+    SyncSession* session) {
   syncable::ScopedDirLookup dir(session->context()->directory_manager(),
                                 session->context()->account_name());
   if (!dir.good()) {
     LOG(ERROR) << "Scoped dir lookup failed!";
-    return;
+    return DIRECTORY_LOOKUP_FAILED;
   }
 
   const sessions::UpdateProgress* progress =
       session->status_controller().update_progress();
   if (!progress)
-    return;  // Nothing to do.
+    return NO_ERROR;  // Nothing to do.
 
   syncable::WriteTransaction trans(FROM_HERE, syncable::SYNCER, dir);
   vector<sessions::VerifiedUpdate>::const_iterator it;
@@ -67,6 +68,7 @@ void ProcessUpdatesCommand::ModelChangingExecuteImpl(SyncSession* session) {
   StatusController* status = session->mutable_status_controller();
   status->set_num_consecutive_errors(0);
   status->mutable_update_progress()->ClearVerifiedUpdates();
+  return NO_ERROR;
 }
 
 namespace {