Revert 150990 - [Sync] Avoid unregistering object IDs on shutdown

chrome/browser/sync/glue/sync_backend_host.h

Index: chrome/browser/sync/glue/sync_backend_host.h
===================================================================
--- chrome/browser/sync/glue/sync_backend_host.h	(revision 150991)
+++ chrome/browser/sync/glue/sync_backend_host.h	(working copy)
@@ -179,8 +179,8 @@
   // 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.  This lasts until StopSyncingForShutdown() is called.
+  // Registers the underlying frontend for the given IDs to the
+  // underlying notifier.
   void UpdateRegisteredInvalidationIds(const syncer::ObjectIdSet& ids);
 
   // This starts the SyncerThread running a Syncer object to communicate with
@@ -211,10 +211,9 @@
   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.