[Sync] Avoid unregistering object IDs on shutdown

sync/notifier/invalidation_notifier.cc

Index: sync/notifier/invalidation_notifier.cc
diff --git a/sync/notifier/invalidation_notifier.cc b/sync/notifier/invalidation_notifier.cc
index 3a72f32fa61ace7acc53ca566d9ccfe210599e51..7a2a933a054c3712af4c9a7f3d13c678a1fc88b4 100644
--- a/sync/notifier/invalidation_notifier.cc
+++ b/sync/notifier/invalidation_notifier.cc
@@ -34,10 +34,19 @@ InvalidationNotifier::~InvalidationNotifier() {
   DCHECK(CalledOnValidThread());
 }
 
-void InvalidationNotifier::UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                               const ObjectIdSet& ids) {
+void InvalidationNotifier::SetHandler(const std::string& handler_name,
+                                      SyncNotifierObserver* handler) {
   DCHECK(CalledOnValidThread());
-  invalidation_client_.RegisterIds(helper_.UpdateRegisteredIds(handler, ids));
+  helper_.SetHandler(handler_name, handler);
+}
+
+void InvalidationNotifier::UpdateRegisteredIds(
+    const std::string& handler_name,
+    const ObjectIdSet& ids) {
+  DCHECK(CalledOnValidThread());
+  helper_.UpdateRegisteredIds(handler_name, ids);
+  const ObjectIdSet& all_registered_ids = helper_.GetAllRegisteredIds();

[msw, 2012/08/07 20:09:30]

nit: comment explaining when |ids| won't match 
|all_registered_ids|? (It's not obvious to me)

[akalin, 2012/08/07 23:38:05]

ids is only for |handler_name|/|handler|, but all_registered_ids holds all IDs
regardless of handler.  Do you think this still needs a comment?  Is the comment
in SyncNotifierHelper::GetAllRegisteredIds() insufficient?

[msw, 2012/08/08 00:55:23]

Ok, I was simply confused. I think it's odd that the three notifier
implementations need to [re]register all IDs every time any ID changes, but I'll
just presume that's intended.

+  invalidation_client_.RegisterIds(all_registered_ids);
 }
 
 void InvalidationNotifier::SetUniqueId(const std::string& unique_id) {