[Sync] Avoid unregistering object IDs on shutdown

sync/notifier/sync_notifier_helper.cc

-// 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.
-
-#include "sync/notifier/sync_notifier_helper.h"
-
-#include "base/logging.h"
-
-namespace syncer {
-
-SyncNotifierHelper::SyncNotifierHelper() {}
-SyncNotifierHelper::~SyncNotifierHelper() {}
-
-ObjectIdSet SyncNotifierHelper::UpdateRegisteredIds(
-    SyncNotifierObserver* handler, const ObjectIdSet& ids) {
-  if (ids.empty()) {
-    handlers_.RemoveObserver(handler);
-  } else if (!handlers_.HasObserver(handler)) {
-    handlers_.AddObserver(handler);
-  }
-
-  ObjectIdSet registered_ids(ids);
-  // Remove all existing entries for |handler| and fill |registered_ids| with
-  // the rest.
-  for (ObjectIdHandlerMap::iterator it = id_to_handler_map_.begin();
-       it != id_to_handler_map_.end(); ) {
-    if (it->second == handler) {
-      ObjectIdHandlerMap::iterator erase_it = it;
-      ++it;
-      id_to_handler_map_.erase(erase_it);
-    } else {
-      registered_ids.insert(it->first);
-      ++it;
-    }
-  }
-
-  // Now add the entries for |handler|. We keep track of the last insertion
-  // point so we only traverse the map once to insert all the new entries.
-  ObjectIdHandlerMap::iterator insert_it = id_to_handler_map_.begin();
-  for (ObjectIdSet::const_iterator it = ids.begin(); it != ids.end(); ++it) {
-    insert_it = id_to_handler_map_.insert(insert_it,
-                                          std::make_pair(*it, handler));
-    CHECK_EQ(handler, insert_it->second) << "Duplicate registration for "
-                                         << ObjectIdToString(insert_it->first);
-  }
-  if (logging::DEBUG_MODE) {
-    // The mapping shouldn't contain any handlers that aren't in |handlers_|.
-    for (ObjectIdHandlerMap::const_iterator it = id_to_handler_map_.begin();
-         it != id_to_handler_map_.end(); ++it) {
-      CHECK(handlers_.HasObserver(it->second));
-    }
-  }
-  return registered_ids;
-}
-
-void SyncNotifierHelper::DispatchInvalidationsToHandlers(
-    const ObjectIdPayloadMap& id_payloads,
-    IncomingNotificationSource source) {
-  typedef std::map<SyncNotifierObserver*, ObjectIdPayloadMap> DispatchMap;
-  DispatchMap dispatch_map;
-  for (ObjectIdPayloadMap::const_iterator it = id_payloads.begin();
-       it != id_payloads.end(); ++it) {
-    ObjectIdHandlerMap::const_iterator find_it =
-        id_to_handler_map_.find(it->first);
-    // If we get an invalidation with a source type that we can't map to an
-    // observer, just drop it--the observer was unregistered while the
-    // invalidation was in flight.
-    if (find_it == id_to_handler_map_.end())
-      continue;
-    dispatch_map[find_it->second].insert(*it);
-  }
-
-  if (handlers_.might_have_observers()) {
-    ObserverListBase<SyncNotifierObserver>::Iterator it(handlers_);
-    SyncNotifierObserver* handler = NULL;
-    while ((handler = it.GetNext()) != NULL) {
-      DispatchMap::const_iterator dispatch_it = dispatch_map.find(handler);
-      if (dispatch_it != dispatch_map.end()) {
-        handler->OnIncomingNotification(dispatch_it->second, source);
-      }
-    }
-  }
-}
-
-void SyncNotifierHelper::EmitOnNotificationsEnabled() {
-  FOR_EACH_OBSERVER(SyncNotifierObserver, handlers_, OnNotificationsEnabled());
-}
-
-void SyncNotifierHelper::EmitOnNotificationsDisabled(
-    NotificationsDisabledReason reason) {
-  FOR_EACH_OBSERVER(SyncNotifierObserver, handlers_,
-                    OnNotificationsDisabled(reason));
-}
-
-}  // namespace syncer