Make use of InvalidationService

chrome/browser/invalidation/invalidation_service.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_INVALIDATION_INVALIDATION_FRONTEND_H_
-#define CHROME_BROWSER_INVALIDATION_INVALIDATION_FRONTEND_H_
+#ifndef CHROME_BROWSER_INVALIDATION_INVALIDATION_SERVICE_H_
+#define CHROME_BROWSER_INVALIDATION_INVALIDATION_SERVICE_H_
 
+#include "components/browser_context_keyed_service/browser_context_keyed_service.h"
 #include "sync/notifier/invalidation_util.h"
 #include "sync/notifier/invalidator_state.h"
 
 namespace syncer {
 class InvalidationHandler;
 class AckHandle;
 }  // namespace syncer
 
 namespace invalidation {
 
 // Interface for classes that handle invalidation registrations and send out
 // invalidations to register handlers.
 //
 // Invalidation clients should follow the pattern below:
 //
 // When starting the client:
 //
 //   frontend->RegisterInvalidationHandler(client_handler);
 //
 // When the set of IDs to register changes for the client during its lifetime
 // (i.e., between calls to RegisterInvalidationHandler(client_handler) and
 // UnregisterInvalidationHandler(client_handler):
 //
 //   frontend->UpdateRegisteredInvalidationIds(client_handler, client_ids);
 //
-// To unregister for all invalidations:
+// When shutting down the client for browser shutdown:
 //
 //   frontend->UnregisterInvalidationHandler(client_handler);
 //
+// 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:
+//
+//   frontend->UpdateRegisteredInvalidationIds(client_handler, ObjectIdSet());
+//   frontend->UnregisterInvalidationHandler(client_handler);
+//
 // If an invalidation handler cares about the invalidator state, it should also
 // do the following when starting the client:
 //
 //   invalidator_state = frontend->GetInvalidatorState();
 //
 // It can also do the above in OnInvalidatorStateChange(), or it can use the
 // argument to OnInvalidatorStateChange().
 //
-// It is an error to have registered handlers when an InvalidationFrontend is
-// shut down; clients must ensure that they unregister themselves before then.
-//
-// TODO(rlarocque): This class should extend BrowserContextKeyedService.
+// It is an error to have registered handlers when an
+// InvalidationFrontend is shut down; clients must ensure that they
+// unregister themselves before then. (Depending on the
+// InvalidationFrontend, shutdown may be equivalent to destruction, or
+// a separate function call like Shutdown()).
 //
 // NOTE(akalin): Invalidations that come in during browser shutdown may get
 // dropped.  This won't matter once we have an Acknowledge API, though: see
 // http://crbug.com/78462 and http://crbug.com/124149.
-class InvalidationFrontend {
+//
+// This class inherits from ProfileKeyedService to make it possible to correctly
+// cast from various InvalidationService implementations to ProfileKeyedService
+// in InvalidationServiceFactory.
+class InvalidationService : public BrowserContextKeyedService {
  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::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
@@ skipping 15 matching lines @@
   // Sends an acknowledgement that an invalidation for |id| was successfully
   // handled.
   virtual void AcknowledgeInvalidation(const invalidation::ObjectId& id,
                                        const syncer::AckHandle& ack_handle) = 0;
 
   // Returns the current invalidator state.  When called from within
   // InvalidationHandler::OnInvalidatorStateChange(), this must return
   // the updated state.
   virtual syncer::InvalidatorState GetInvalidatorState() const = 0;
 
+  // Returns the ID belonging to this invalidation client.  Can be used to
+  // prevent the receipt of notifications of our own changes.
+  virtual std::string GetInvalidatorClientId() const = 0;
+
  protected:
-  virtual ~InvalidationFrontend() { }
+  virtual ~InvalidationService() { }
 };
 
 }  // namespace invalidation
 
-#endif  // CHROME_BROWSER_INVALIDATION_INVALIDATION_FRONTEND_H_
+#endif  // CHROME_BROWSER_INVALIDATION_INVALIDATION_SERVICE_H_