Avoid useless SYNC_CYCLE_CONTINUATION sync cycle

chrome/browser/sync/engine/process_updates_command.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/sync/engine/process_updates_command.h"
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/location.h"
@@ skipping 14 matching lines @@
 using sessions::UpdateProgress;
 
 ProcessUpdatesCommand::ProcessUpdatesCommand() {}
 ProcessUpdatesCommand::~ProcessUpdatesCommand() {}
 
 std::set<ModelSafeGroup> ProcessUpdatesCommand::GetGroupsToChange(
     const sessions::SyncSession& session) const {
   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;
   for (it = progress->VerifiedUpdatesBegin();
        it != progress->VerifiedUpdatesEnd();
        ++it) {
     const sync_pb::SyncEntity& update = it->second;
 
     if (it->first != VERIFY_SUCCESS && it->first != VERIFY_UNDELETE)
       continue;
     switch (ProcessUpdate(dir, update, &trans)) {
       case SUCCESS_PROCESSED:
       case SUCCESS_STORED:
         break;
       default:
         NOTREACHED();
         break;
     }
   }
 
   StatusController* status = session->mutable_status_controller();
   status->set_num_consecutive_errors(0);
   status->mutable_update_progress()->ClearVerifiedUpdates();
+  return NO_ERROR;
 }
 
 namespace {
 // Returns true if the entry is still ok to process.
 bool ReverifyEntry(syncable::WriteTransaction* trans, const SyncEntity& entry,
                    syncable::MutableEntry* same_id) {
 
   const bool deleted = entry.has_deleted() && entry.deleted();
   const bool is_directory = entry.IsFolder();
   const syncable::ModelType model_type = entry.GetModelType();
@@ skipping 63 matching lines @@
     // Force application of this update, no matter what.
     target_entry.Put(syncable::IS_UNAPPLIED_UPDATE, true);
   }
 
   SyncerUtil::UpdateServerFieldsFromUpdate(&target_entry, update, name);
 
   return SUCCESS_PROCESSED;
 }
 
 }  // namespace browser_sync