Delete the PreferenceMACs on profile deletion.

components/prefs/overlay_user_pref_store.cc

Index: components/prefs/overlay_user_pref_store.cc
diff --git a/components/prefs/overlay_user_pref_store.cc b/components/prefs/overlay_user_pref_store.cc
index 55f3f687e2e456645ae4605a0bb5bc5c98322c83..76109c478581cd2bfea2ec5ad5fdbfb151d943d1 100644
--- a/components/prefs/overlay_user_pref_store.cc
+++ b/components/prefs/overlay_user_pref_store.cc
@@ -197,6 +197,10 @@ void OverlayUserPrefStore::ClearMutableValues() {
   }
 }
 
+void OverlayUserPrefStore::OnStoreDeletionFromDisk() {
+  underlay_->OnStoreDeletionFromDisk();
+}
+
 OverlayUserPrefStore::~OverlayUserPrefStore() {
   overlay_->RemoveObserver(overlay_observer_.get());
   underlay_->RemoveObserver(underlay_observer_.get());