Delete the PreferenceMACs on profile deletion.

services/preferences/tracked/segregated_pref_store.cc

Index: services/preferences/tracked/segregated_pref_store.cc
diff --git a/services/preferences/tracked/segregated_pref_store.cc b/services/preferences/tracked/segregated_pref_store.cc
index ced018e7c67d4809fe8c9a93d9e7a363c6a70f2f..1fae1507c0c400bbc0c2c8132b1cba9c172dbbda 100644
--- a/services/preferences/tracked/segregated_pref_store.cc
+++ b/services/preferences/tracked/segregated_pref_store.cc
@@ -178,6 +178,11 @@ void SegregatedPrefStore::ClearMutableValues() {
   NOTIMPLEMENTED();
 }
 
+void SegregatedPrefStore::OnStoreDeletionFromDisk() {
+  default_pref_store_->OnStoreDeletionFromDisk();
+  selected_pref_store_->OnStoreDeletionFromDisk();
+}
+
 SegregatedPrefStore::~SegregatedPrefStore() {
   default_pref_store_->RemoveObserver(&aggregating_observer_);
   selected_pref_store_->RemoveObserver(&aggregating_observer_);