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

sync/internal_api/sync_rollback_manager_base.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_base.h"
 
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/internal_components_factory.h"
 #include "sync/internal_api/public/read_node.h"
 #include "sync/internal_api/public/read_transaction.h"
@@ skipping 314 matching lines @@
   entry.PutUniqueServerTag(folder);
   entry.PutNonUniqueName(folder);
   entry.PutIsDel(false);
   entry.PutIsDir(true);
 
   sync_pb::EntitySpecifics specifics;
   AddDefaultFieldValue(BOOKMARKS, &specifics);
   entry.PutSpecifics(specifics);
 }
 
+ObserverList<SyncManager::Observer>* SyncRollbackManagerBase::GetObservers() {
+  return &observers_;
+}
+
 void SyncRollbackManagerBase::RegisterDirectoryTypeDebugInfoObserver(
     syncer::TypeDebugInfoObserver* observer) {}
 
 void SyncRollbackManagerBase::UnregisterDirectoryTypeDebugInfoObserver(
     syncer::TypeDebugInfoObserver* observer) {}
 
 bool SyncRollbackManagerBase::HasDirectoryTypeDebugInfoObserver(
     syncer::TypeDebugInfoObserver* observer) { return false; }
 
 void SyncRollbackManagerBase::RequestEmitDebugInfo() {}
 
 }  // namespace syncer