Implement new SyncAPI and convert Preferences to it.

chrome/browser/sync/api/sync_event_processor.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_API_SYNC_EVENT_PROCESSOR_H_
+#define CHROME_BROWSER_SYNC_API_SYNC_EVENT_PROCESSOR_H_
+#pragma once
+
+#include <vector>
+
+class SyncEvent;
+
+typedef std::vector<SyncEvent> SyncEventList;
+
+// An interface for services that handle receiving SyncEvents.
+class SyncEventProcessor {
+ public:
+  virtual ~SyncEventProcessor() {}
+
+  // Process a list of SyncEvents.
+  virtual void ProcessSyncEvents(const SyncEventList& event_list) = 0;
+};
+
+
+#endif  // CHROME_BROWSER_SYNC_API_SYNC_EVENT_PROCESSOR_H_