Plumb invalidations from Tango to the extensions code for the Push Messaging API.

chrome/browser/sync/invalidation_frontend.h

+// Copyright (c) 2012 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_INVALIDATION_FRONTEND_H_
+#define CHROME_BROWSER_SYNC_INVALIDATION_FRONTEND_H_
+
+#include "sync/notifier/invalidation_util.h"
+
+namespace syncer {
+class SyncNotifierObserver;
+}  // namespace syncer
+
+// Interface for classes that handle invalidation registrations and send out
+// invalidations to register handlers.
+class InvalidationFrontend {
+ public:
+  // Starts sending notifications to |handler|.  |handler| must not be NULL,
+  // and it must not already be registered.
+  //
+  // Handler registrations are persisted across restarts of sync.
+  virtual void RegisterInvalidationHandler(
+      syncer::SyncNotifierObserver* handler) = 0;
+
+  // Updates the set of ObjectIds associated with |handler|.  |handler| must
+  // not be NULL, and must already be registered.  An ID must be registered for
+  // at most one handler.
+  //
+  // Registered IDs are persisted across restarts of sync.
+  virtual void UpdateRegisteredInvalidationIds(
+      syncer::SyncNotifierObserver* handler,
+      const syncer::ObjectIdSet& ids) = 0;
+
+  // Stops sending notifications to |handler|.  |handler| must not be NULL, and
+  // it must already be registered.  Note that this doesn't unregister the IDs
+  // associated with |handler|.
+  //
+  // Handler registrations are persisted across restarts of sync.
+  virtual void UnregisterInvalidationHandler(
+      syncer::SyncNotifierObserver* handler) = 0;
+
+ protected:
+  virtual ~InvalidationFrontend() { }
+};
+
+#endif  // CHROME_BROWSER_SYNC_INVALIDATION_FRONTEND_H_