[Sync] Minor refactor around SyncCycle and ModelTypeSet usage.

components/sync/engine_impl/syncer.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 "components/sync/engine_impl/syncer.h"
 
 #include <memory>
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
@@ skipping 46 matching lines @@
   if (nudge_tracker->IsGetUpdatesRequired() ||
       cycle->context()->ShouldFetchUpdatesBeforeCommit()) {
     VLOG(1) << "Downloading types " << ModelTypeSetToString(request_types);
     if (!DownloadAndApplyUpdates(&request_types, cycle,
                                  NormalGetUpdatesDelegate(*nudge_tracker),
                                  kCreateMobileBookmarksFolder)) {
       return HandleCycleEnd(cycle, nudge_tracker->GetLegacySource());
     }
   }
 
-  VLOG(1) << "Committing from types " << ModelTypeSetToString(request_types);
   CommitProcessor commit_processor(
       cycle->context()->model_type_registry()->commit_contributor_map());
   SyncerError commit_result = BuildAndPostCommits(request_types, nudge_tracker,
                                                   cycle, &commit_processor);
   cycle->mutable_status_controller()->set_commit_result(commit_result);
 
   return HandleCycleEnd(cycle, nudge_tracker->GetLegacySource());
 }
 
 bool Syncer::ConfigureSyncShare(
-    ModelTypeSet request_types,
+    const ModelTypeSet& request_types,
     sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source,
     SyncCycle* cycle) {
   base::AutoReset<bool> is_syncing(&is_syncing_, true);
 
   // It is possible during configuration that datatypes get unregistered from
   // ModelTypeRegistry before scheduled configure sync cycle gets executed.
   // This happens either because DataTypeController::LoadModels fail and type
   // need to be stopped or during shutdown when all datatypes are stopped. When
   // it happens we should adjust set of types to download to only include
   // registered types.
-  request_types.RetainAll(cycle->context()->GetEnabledTypes());
-  VLOG(1) << "Configuring types " << ModelTypeSetToString(request_types);
+  ModelTypeSet still_enabled_types =
+      Intersection(request_types, cycle->context()->GetEnabledTypes());
+  VLOG(1) << "Configuring types " << ModelTypeSetToString(still_enabled_types);
   HandleCycleBegin(cycle);
-  DownloadAndApplyUpdates(&request_types, cycle,
+  DownloadAndApplyUpdates(&still_enabled_types, cycle,
                           ConfigureGetUpdatesDelegate(source),
                           kCreateMobileBookmarksFolder);
   return HandleCycleEnd(cycle, source);
 }
 
 bool Syncer::PollSyncShare(ModelTypeSet request_types, SyncCycle* cycle) {
   base::AutoReset<bool> is_syncing(&is_syncing_, true);
   VLOG(1) << "Polling types " << ModelTypeSetToString(request_types);
   HandleCycleBegin(cycle);
   DownloadAndApplyUpdates(&request_types, cycle, PollGetUpdatesDelegate(),
@@ skipping 36 matching lines @@
                                        cycle->mutable_status_controller());
 
     cycle->context()->set_hierarchy_conflict_detected(
         cycle->status_controller().num_hierarchy_conflicts() > 0);
     cycle->SendEventNotification(SyncCycleEvent::STATUS_CHANGED);
   }
 
   return !ExitRequested();
 }
 
-SyncerError Syncer::BuildAndPostCommits(ModelTypeSet request_types,
+SyncerError Syncer::BuildAndPostCommits(const ModelTypeSet& request_types,
                                         NudgeTracker* nudge_tracker,
                                         SyncCycle* cycle,
                                         CommitProcessor* commit_processor) {
+  VLOG(1) << "Committing from types " << ModelTypeSetToString(request_types);
+
   // The ExitRequested() check is unnecessary, since we should start getting
   // errors from the ServerConnectionManager if an exist has been requested.
   // However, it doesn't hurt to check it anyway.
   while (!ExitRequested()) {
     std::unique_ptr<Commit> commit(
         Commit::Init(request_types, cycle->context()->GetEnabledTypes(),
                      cycle->context()->max_commit_batch_size(),
                      cycle->context()->account_name(),
                      cycle->context()->directory()->cache_guid(),
                      cycle->context()->cookie_jar_mismatch(),
@@ skipping 29 matching lines @@
   bool success =
       !HasSyncerError(cycle->status_controller().model_neutral_state());
   if (success && source == sync_pb::GetUpdatesCallerInfo::PERIODIC) {
     cycle->mutable_status_controller()->UpdatePollTime();
   }
 
   return success;
 }
 
 }  // namespace syncer