Delete the PreferenceMACs on profile deletion.

components/prefs/json_pref_store.cc

Index: components/prefs/json_pref_store.cc
diff --git a/components/prefs/json_pref_store.cc b/components/prefs/json_pref_store.cc
index 0b6b0f1803eb1ddab599e6c5bd5b1627ead7b5cd..31280be850796ab4ef71055b03b11388285a3da3 100644
--- a/components/prefs/json_pref_store.cc
+++ b/components/prefs/json_pref_store.cc
@@ -393,6 +393,11 @@ void JsonPrefStore::ClearMutableValues() {
   NOTIMPLEMENTED();
 }
 
+void JsonPrefStore::OnStoreDeletionFromDisk() {
+  if (pref_filter_)
+    pref_filter_->OnStoreDeletionFromDisk();
+}
+
 void JsonPrefStore::OnFileRead(std::unique_ptr<ReadResult> read_result) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);