Refactor sync notifier out of sync api.

chrome/browser/sync/notifier/sync_notifier_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_NOTIFIER_SYNC_NOTIFIER_OBSERVER_H_
+#define CHROME_BROWSER_SYNC_NOTIFIER_SYNC_NOTIFIER_OBSERVER_H_
+
+#include <string>
+
+#include "chrome/browser/sync/sessions/session_state.h"
+
+namespace sync_notifier {
+
+class SyncNotifierObserver {
+ public:
+  SyncNotifierObserver() {}
+  virtual ~SyncNotifierObserver() {}
+
+  virtual void OnIncomingNotification(
+      const browser_sync::sessions::TypePayloadMap& type_payloads) = 0;
+  virtual void OnNotificationStateChange(bool notifications_enabled) = 0;
+
+  // TODO(nileshagrawal): Find a way to hide state handling inside the
+  // sync notifier implementation.
+  virtual void StoreState(const std::string& state) = 0;
+};
+}  // namespace sync_notifier
+#endif  // CHROME_BROWSER_SYNC_NOTIFIER_SYNC_NOTIFIER_OBSERVER_H_