[Invalidations] Add GetInvalidatorState() to Invalidator{,Frontend}

sync/notifier/invalidator.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.
 //
 // Interface to the invalidator, which is an object that receives
 // invalidations for registered object IDs. The corresponding
 // InvalidationHandler is notifier when such an event occurs.
 
 #ifndef SYNC_NOTIFIER_INVALIDATOR_H_
 #define SYNC_NOTIFIER_INVALIDATOR_H_
 
 #include <string>
 
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/notifier/invalidation_util.h"
+#include "sync/notifier/invalidator_state.h"
 #include "sync/notifier/object_id_state_map.h"
 
 namespace syncer {
 class InvalidationHandler;
 
 class Invalidator {
  public:
   Invalidator() {}
   virtual ~Invalidator() {}
 
@@ skipping 16 matching lines @@
   // Note that there's no call to UpdateRegisteredIds() -- this is because the
   // invalidation API persists registrations across browser restarts.
   //
   // When permanently shutting down the client, e.g. when disabling the related
   // feature:
   //
   //   invalidator->UpdateRegisteredIds(client_handler, ObjectIdSet());
   //   invalidator->UnregisterHandler(client_handler);
 
   // Starts sending notifications to |handler|.  |handler| must not be NULL,
-  // and it must already be registered.
+  // and it must not already be registered.
   virtual void RegisterHandler(InvalidationHandler* 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.
   virtual void UpdateRegisteredIds(InvalidationHandler* handler,
                                    const 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|.
   virtual void UnregisterHandler(InvalidationHandler* handler) = 0;
 
+  // Returns the current invalidator state.  When called from within
+  // InvalidationHandler::OnInvalidatorStateChange(), this must return
+  // the updated state.
+  virtual InvalidatorState GetInvalidatorState() const = 0;
+
   // SetUniqueId must be called once, before any call to
   // UpdateCredentials.  |unique_id| should be a non-empty globally
   // unique string.
   virtual void SetUniqueId(const std::string& unique_id) = 0;
 
   // SetState must be called once, before any call to
   // UpdateCredentials.  |state| may be empty.
   // Deprecated in favour of InvalidationStateTracker persistence.
   virtual void SetStateDeprecated(const std::string& state) = 0;
 
   // The observers won't be notified of any notifications until
   // UpdateCredentials is called at least once. It can be called more than
   // once.
   virtual void UpdateCredentials(
       const std::string& email, const std::string& token) = 0;
 
   // This is here only to support the old p2p notification implementation,
   // which is still used by sync integration tests.
   // TODO(akalin): Remove this once we move the integration tests off p2p
   // notifications.
-  virtual void SendNotification(const ObjectIdStateMap& id_state_map) = 0;
+  virtual void SendInvalidation(const ObjectIdStateMap& id_state_map) = 0;
 };
 }  // namespace syncer
 
 #endif  // SYNC_NOTIFIER_INVALIDATOR_H_