Disable history delete directives when sessions are encrypted.

chrome/browser/sync/sync_prefs.cc

Index: chrome/browser/sync/sync_prefs.cc
diff --git a/chrome/browser/sync/sync_prefs.cc b/chrome/browser/sync/sync_prefs.cc
index a5c58e82ea609d9851c97fa00478670f53149926..57e4672daf4edc76af0af8f150d1021f2328765a 100644
--- a/chrome/browser/sync/sync_prefs.cc
+++ b/chrome/browser/sync/sync_prefs.cc
@@ -214,10 +214,6 @@ void SyncPrefs::SetKeepEverythingSynced(bool keep_everything_synced) {
                             keep_everything_synced);
 }
 
-// TODO(akalin): If encryption is turned on for all data types,
-// history delete directives are useless and so we shouldn't bother
-// enabling them.
-
 syncer::ModelTypeSet SyncPrefs::GetPreferredDataTypes(
     syncer::ModelTypeSet registered_types) const {
   DCHECK(CalledOnValidThread());