Delete the PreferenceMACs on profile deletion.

services/preferences/persistent_pref_store_impl.cc

Index: services/preferences/persistent_pref_store_impl.cc
diff --git a/services/preferences/persistent_pref_store_impl.cc b/services/preferences/persistent_pref_store_impl.cc
index 09357e3cc6ddc5e2634c8af0dbd7bc4d404ea7b2..af8252b073409bccb36df7ef4bbb09e564ead2d8 100644
--- a/services/preferences/persistent_pref_store_impl.cc
+++ b/services/preferences/persistent_pref_store_impl.cc
@@ -136,6 +136,9 @@ class PersistentPrefStoreImpl::Connection : public mojom::PersistentPrefStore {
     pref_store_->SchedulePendingLossyWrites();
   }
   void ClearMutableValues() override { pref_store_->ClearMutableValues(); }
+  void OnStoreDeletionFromDisk() override {
+    pref_store_->OnStoreDeletionFromDisk();
+  }
 
   void OnConnectionError() { pref_store_->OnConnectionError(this); }
 
@@ -281,6 +284,10 @@ void PersistentPrefStoreImpl::ClearMutableValues() {
   backing_pref_store_->ClearMutableValues();
 }
 
+void PersistentPrefStoreImpl::OnStoreDeletionFromDisk() {
+  backing_pref_store_->OnStoreDeletionFromDisk();
+}
+
 void PersistentPrefStoreImpl::OnConnectionError(Connection* connection) {
   connections_.erase(connection);
 }