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

sync/internal_api/sync_rollback_manager_base.h

 // 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.
 
 #ifndef SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_BASE_H_
 #define SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_BASE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 95 matching lines @@
   virtual void HandleCalculateChangesChangeEventFromSyncer(
       const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
       syncable::BaseTransaction* trans,
       std::vector<int64>* entries_changed) OVERRIDE;
 
   // syncable::TransactionObserver implementation.
   virtual void OnTransactionWrite(
       const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
       ModelTypeSet models_with_changes) OVERRIDE;
 
+ protected:
+  ObserverList<SyncManager::Observer>* GetObservers();
+
   virtual void RegisterDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) OVERRIDE;
   virtual void UnregisterDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) OVERRIDE;
   virtual bool HasDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) OVERRIDE;
   virtual void RequestEmitDebugInfo() OVERRIDE;
 
  private:
   void NotifyInitializationSuccess();
@@ skipping 15 matching lines @@
   base::WeakPtrFactory<SyncRollbackManagerBase> weak_ptr_factory_;
 
   scoped_ptr<SyncEncryptionHandler> dummy_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncRollbackManagerBase);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_SYNC_ROLLBACK_MANAGER_BASE_H_