Sync: Remove flag to explicitly enable history delete directive sync.

chrome/browser/sync/profile_sync_components_factory_impl.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 "base/command_line.h"
 #include "build/build_config.h"
 #include "chrome/browser/bookmarks/bookmark_model_factory.h"
 #include "chrome/browser/extensions/app_notification_manager.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
@@ skipping 195 matching lines @@
         new AutofillProfileDataTypeController(this, profile_, pss));
   }
 
   // App notifications sync is enabled by default.  Register unless explicitly
   // disabled.
   if (!command_line_->HasSwitch(switches::kDisableSyncAppNotifications)) {
     pss->RegisterDataTypeController(
         new AppNotificationDataTypeController(this, profile_, pss));
   }
 
-  // History delete directives sync is disabled by default.  Register only if
-  // explicitly enabled.
-  if (command_line_->HasSwitch(switches::kEnableSyncHistoryDeleteDirectives)) {
+  // Unless it is explicitly disabled, history delete directive sync is
+  // enabled whenever full history sync is enabled.
+  if (command_line_->HasSwitch(switches::kHistoryEnableFullHistorySync) &&
+      !command_line_->HasSwitch(
+          switches::kDisableSyncHistoryDeleteDirectives)) {
     pss->RegisterDataTypeController(
         new UIDataTypeController(
             syncer::HISTORY_DELETE_DIRECTIVES, this, profile_, pss));
   }
 }
 
 DataTypeManager* ProfileSyncComponentsFactoryImpl::CreateDataTypeManager(
     const syncer::WeakHandle<syncer::DataTypeDebugInfoListener>&
         debug_info_listener,
     SyncBackendHost* backend,
@@ skipping 137 matching lines @@
 ProfileSyncComponentsFactory::SyncComponents
     ProfileSyncComponentsFactoryImpl::CreateSessionSyncComponents(
        ProfileSyncService* profile_sync_service,
         DataTypeErrorHandler* error_handler) {
   SessionModelAssociator* model_associator =
       new SessionModelAssociator(profile_sync_service, error_handler);
   SessionChangeProcessor* change_processor =
       new SessionChangeProcessor(error_handler, model_associator);
   return SyncComponents(model_associator, change_processor);
 }