Add a ClientAction used by SyncRollbackManager to notify PSS that rollback is

sync/internal_api/sync_rollback_manager.cc

 // Copyright 2014 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 "sync/internal_api/sync_rollback_manager.h"
 
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/read_node.h"
 #include "sync/internal_api/public/read_transaction.h"
 #include "sync/internal_api/public/util/syncer_error.h"
@@ skipping 49 matching lines @@
     CHECK(workers_.find(group) == workers_.end());
     workers_[group] = workers[i];
   }
 
   rollback_ready_types_ = GetUserShare()->directory->InitialSyncEndedTypes();
   rollback_ready_types_.RetainAll(BackupTypes());
 }
 
 void SyncRollbackManager::StartSyncingNormally(
     const ModelSafeRoutingInfo& routing_info){
+  if (rollback_ready_types_.Empty()) {
+    NotifyRollbackDone();
+    return;
+  }
+
   std::map<ModelType, syncable::Directory::Metahandles> to_delete;
-
   {
     WriteTransaction trans(FROM_HERE, GetUserShare());
     syncable::Directory::Metahandles unsynced;
     GetUserShare()->directory->GetUnsyncedMetaHandles(trans.GetWrappedTrans(),
                                                       &unsynced);
     for (size_t i = 0; i < unsynced.size(); ++i) {
       syncable::MutableEntry e(trans.GetWrappedWriteTrans(),
                                syncable::GET_BY_HANDLE, unsynced[i]);
       if (!e.good() || e.GetIsDel() || e.GetId().ServerKnows())
         continue;
@@ skipping 11 matching lines @@
 
   for (std::map<ModelType, syncable::Directory::Metahandles>::iterator it =
       to_delete.begin(); it != to_delete.end(); ++it) {
     ModelSafeGroup group = routing_info.find(it->first)->second;
     CHECK(workers_.find(group) != workers_.end());
     workers_[group]->DoWorkAndWaitUntilDone(
         base::Bind(&SyncRollbackManager::DeleteOnWorkerThread,
                    base::Unretained(this),
                    it->first, it->second));
   }
+
+  NotifyRollbackDone();
 }
 
 SyncerError SyncRollbackManager::DeleteOnWorkerThread(
     ModelType type, std::vector<int64> handles) {
   CHECK(change_delegate_);
 
   {
     ChangeRecordList deletes;
     WriteTransaction trans(FROM_HERE, GetUserShare());
     for (size_t i = 0; i < handles.size(); ++i) {
@@ skipping 10 matching lines @@
     }
 
     change_delegate_->OnChangesApplied(type, 1, &trans,
                                        MakeImmutable(&deletes));
   }
 
   change_delegate_->OnChangesComplete(type);
   return SYNCER_OK;
 }
 
+void SyncRollbackManager::NotifyRollbackDone() {
+  SyncProtocolError error;
+  error.action = ROLLBACK_DONE;
+  FOR_EACH_OBSERVER(SyncManager::Observer, *GetObservers(),
+                    OnActionableError(error));
+}
+
 }  // namespace syncer