Delete the PreferenceMACs on profile deletion.

components/prefs/pref_service.cc

Index: components/prefs/pref_service.cc
diff --git a/components/prefs/pref_service.cc b/components/prefs/pref_service.cc
index 6abc09bcb46b56df74c3415279c2e6c7ef849b5a..2d819f9e77852417961787139a1ffb23da5af76d 100644
--- a/components/prefs/pref_service.cc
+++ b/components/prefs/pref_service.cc
@@ -374,6 +374,10 @@ void PrefService::ClearMutableValues() {
   user_pref_store_->ClearMutableValues();
 }
 
+void PrefService::OnStoreDeletionFromDisk() {
+  user_pref_store_->OnStoreDeletionFromDisk();
+}
+
 void PrefService::Set(const std::string& path, const base::Value& value) {
   SetUserPrefValue(path, value.CreateDeepCopy());
 }