[Sync] Split DirectoryChangeListener for thread-safety

chrome/browser/sync/js_transaction_observer.h

+// 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.
+
+#ifndef CHROME_BROWSER_SYNC_JS_TRANSACTION_OBSERVER_H_
+#define CHROME_BROWSER_SYNC_JS_TRANSACTION_OBSERVER_H_
+#pragma once
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/threading/non_thread_safe.h"
+#include "chrome/browser/sync/syncable/transaction_observer.h"
+
+namespace browser_sync {
+
+class JsEventRouter;
+
+// Routes SyncManager events to a JsEventRouter.
+class JsTransactionObserver : public syncable::TransactionObserver {
+ public:
+  // |parent_router| must be non-NULL and must outlive this object.
+  explicit JsTransactionObserver(JsEventRouter* parent_router);
+
+  virtual ~JsTransactionObserver();
+
+  // syncable::TransactionObserver implementation.
+  virtual void OnTransactionStart(
+      const tracked_objects::Location& location,
+      const syncable::WriterTag& writer) OVERRIDE;
+  virtual void OnTransactionMutate(
+      const tracked_objects::Location& location,
+      const syncable::WriterTag& writer,
+      const syncable::OriginalEntries& originals,
+      const syncable::ModelTypeBitSet& models_with_changes) OVERRIDE;
+  virtual void OnTransactionEnd(
+      const tracked_objects::Location& location,
+      const syncable::WriterTag& writer) OVERRIDE;
+
+ private:
+  base::NonThreadSafe non_thread_safe_;
+  JsEventRouter* parent_router_;
+
+  DISALLOW_COPY_AND_ASSIGN(JsTransactionObserver);
+};
+
+}  // namespace browser_sync
+
+#endif  // CHROME_BROWSER_SYNC_JS_TRANSACTION_OBSERVER_H_