Add InvalidationStateTracker::Forget() to erase an entry from storage.

sync/notifier/chrome_invalidation_client.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.
 //
 // A simple wrapper around invalidation::InvalidationClient that
 // handles all the startup/shutdown details and hookups.
 
 #ifndef SYNC_NOTIFIER_CHROME_INVALIDATION_CLIENT_H_
 #define SYNC_NOTIFIER_CHROME_INVALIDATION_CLIENT_H_
 
@@ skipping 103 matching lines @@
   // notifier::PushClientObserver implementation.
   virtual void OnNotificationsEnabled() OVERRIDE;
   virtual void OnNotificationsDisabled(
       notifier::NotificationsDisabledReason reason) OVERRIDE;
   virtual void OnIncomingNotification(
       const notifier::Notification& notification) OVERRIDE;
 
  private:
   friend class ChromeInvalidationClientTest;
 
+  void DoRegistrationUpdate();
+
   void Stop();
 
   NotificationsDisabledReason GetState() const;
 
   void EmitStateChange();
 
   void EmitInvalidation(const ObjectIdPayloadMap& id_payloads);
 
   // Owned by |chrome_system_resources_|.
   notifier::PushClient* const push_client_;
@@ skipping 10 matching lines @@
   // NO_NOTIFICATION_ERROR meaning notifications are enabled).
   NotificationsDisabledReason ticl_state_;
   NotificationsDisabledReason push_client_state_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeInvalidationClient);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_NOTIFIER_CHROME_INVALIDATION_CLIENT_H_