Delete the PreferenceMACs on profile deletion.

services/preferences/public/cpp/persistent_pref_store_client.cc

Index: services/preferences/public/cpp/persistent_pref_store_client.cc
diff --git a/services/preferences/public/cpp/persistent_pref_store_client.cc b/services/preferences/public/cpp/persistent_pref_store_client.cc
index 3131d4ad2c3a4cd75c3b5aaddbfe7de70294b403..1e6959e4ee562f7339b95f10b5569bdd1f5e58a0 100644
--- a/services/preferences/public/cpp/persistent_pref_store_client.cc
+++ b/services/preferences/public/cpp/persistent_pref_store_client.cc
@@ -243,6 +243,11 @@ void PersistentPrefStoreClient::ClearMutableValues() {
   return pref_store_->ClearMutableValues();
 }
 
+void PersistentPrefStoreClient::OnStoreDeletionFromDisk() {
+  DCHECK(pref_store_);
+  return pref_store_->OnStoreDeletionFromDisk();
+}
+
 PersistentPrefStoreClient::~PersistentPrefStoreClient() {
   if (!pref_store_)
     return;