[Sync] Make EnableDisableSingleClientTest more robust.

chrome/browser/sync/test/integration/profile_sync_service_harness.cc

Index: chrome/browser/sync/test/integration/profile_sync_service_harness.cc
diff --git a/chrome/browser/sync/test/integration/profile_sync_service_harness.cc b/chrome/browser/sync/test/integration/profile_sync_service_harness.cc
index 4e552de4cffa9a4fee54372652d93496f0bc65b4..97f45645a54a9bc05db265383cc7f7fa1849b5c1 100644
--- a/chrome/browser/sync/test/integration/profile_sync_service_harness.cc
+++ b/chrome/browser/sync/test/integration/profile_sync_service_harness.cc
@@ -329,6 +329,12 @@ bool ProfileSyncServiceHarness::EnableSyncForDatatype(
     return false;
   }
 
+  if (!syncer::UserSelectableTypes().Has(datatype)) {
+    LOG(ERROR) << "Can only enable user selectable types, requested "
+               << syncer::ModelTypeToString(datatype);
+    return false;
+  }
+
   syncer::ModelTypeSet synced_datatypes = service()->GetPreferredDataTypes();
   if (synced_datatypes.Has(datatype)) {
     DVLOG(1) << "EnableSyncForDatatype(): Sync already enabled for datatype "
@@ -362,6 +368,12 @@ bool ProfileSyncServiceHarness::DisableSyncForDatatype(
     return false;
   }
 
+  if (!syncer::UserSelectableTypes().Has(datatype)) {
+    LOG(ERROR) << "Can only disable user selectable types, requested "
+               << syncer::ModelTypeToString(datatype);
+    return false;
+  }
+
   syncer::ModelTypeSet synced_datatypes = service()->GetPreferredDataTypes();
   if (!synced_datatypes.Has(datatype)) {
     DVLOG(1) << "DisableSyncForDatatype(): Sync already disabled for datatype "