[Sync] Avoid unregistering object IDs on shutdown

chrome/browser/sync/glue/sync_backend_host.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_GLUE_SYNC_BACKEND_HOST_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 161 matching lines @@
       const syncer::SyncCredentials& credentials,
       bool delete_sync_data_folder,
       syncer::SyncManagerFactory* sync_manager_factory,
       syncer::UnrecoverableErrorHandler* unrecoverable_error_handler,
       syncer::ReportUnrecoverableErrorFunction
           report_unrecoverable_error_function);
 
   // Called on |frontend_loop| to update SyncCredentials.
   void UpdateCredentials(const syncer::SyncCredentials& credentials);
 
-  // Registers the underlying frontend for the given IDs to the
-  // underlying notifier.
+  // Registers the underlying frontend for the given IDs to the underlying
+  // notifier.  This lasts until StopSyncingForShutdown() is called.
   void UpdateRegisteredInvalidationIds(const syncer::ObjectIdSet& ids);
 
   // This starts the SyncerThread running a Syncer object to communicate with
   // sync servers.  Until this is called, no changes will leave or enter this
   // browser from the cloud / sync servers.
   // Called on |frontend_loop_|.
   virtual void StartSyncingWithServer();
 
   // Called on |frontend_loop_| to asynchronously set a new passphrase for
   // encryption. Note that it is an error to call SetEncryptionPassphrase under
@@ skipping 10 matching lines @@
 
   // Called on |frontend_loop_| to use the provided passphrase to asynchronously
   // attempt decryption. Returns false immediately if the passphrase could not
   // be used to decrypt a locally cached copy of encrypted keys; returns true
   // otherwise. If new encrypted keys arrive during the asynchronous call,
   // OnPassphraseRequired may be triggered at a later time. It is an error to
   // call this when there are no pending keys.
   bool SetDecryptionPassphrase(const std::string& passphrase)
       WARN_UNUSED_RESULT;
 
-  // Called on |frontend_loop_| to kick off shutdown procedure. After this,
-  // no further sync activity will occur with the sync server and no further
+  // Called on |frontend_loop_| to kick off shutdown procedure. After this, no
+  // further sync activity will occur with the sync server and no further
   // change applications will occur from changes already downloaded.
+  // Furthermore, no notifications will be sent to any invalidation handler.
   virtual void StopSyncingForShutdown();
 
   // Called on |frontend_loop_| to kick off shutdown.
   // |sync_disabled| indicates if syncing is being disabled or not.
   // See the implementation and Core::DoShutdown for details.
   // Must be called *after* StopSyncingForShutdown.
   void Shutdown(bool sync_disabled);
 
   // Changes the set of data types that are currently being synced.
   // The ready_task will be run when configuration is done with the
@@ skipping 302 matching lines @@
 
   // UI-thread cache of the last SyncSessionSnapshot received from syncapi.
   syncer::sessions::SyncSessionSnapshot last_snapshot_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_