Introduce a temporary workaround to ensure tracked preferences set to empty list/dict are not confu…

base/prefs/pref_service.cc

Index: base/prefs/pref_service.cc
diff --git a/base/prefs/pref_service.cc b/base/prefs/pref_service.cc
index 296e6f2a9130ee2a599b3c485657b47205eb0a6b..4c707a50d6c231137055bf27b7930f945aa3045e 100644
--- a/base/prefs/pref_service.cc
+++ b/base/prefs/pref_service.cc
@@ -297,6 +297,10 @@ const base::Value* PrefService::GetDefaultPrefValue(const char* path) const {
   return value;
 }
 
+void PrefService::MarkUserStoreNeedsEmptyValue(const std::string& key) const {
+  user_pref_store_->MarkNeedsEmptyValue(key);
+}
+
 const base::ListValue* PrefService::GetList(const char* path) const {
   DCHECK(CalledOnValidThread());