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

chrome/browser/sync/profile_sync_components_factory_impl.cc

Index: chrome/browser/sync/profile_sync_components_factory_impl.cc
diff --git a/chrome/browser/sync/profile_sync_components_factory_impl.cc b/chrome/browser/sync/profile_sync_components_factory_impl.cc
index a5999cca6cb328e92b5ebe6ab444a3bf4123760c..8d0bddffc43e838b99c2d04c8d665f119171eb89 100644
--- a/chrome/browser/sync/profile_sync_components_factory_impl.cc
+++ b/chrome/browser/sync/profile_sync_components_factory_impl.cc
@@ -213,9 +213,11 @@ void ProfileSyncComponentsFactoryImpl::RegisterDesktopDataTypes(
         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));