Update from https://crrev.com/309415

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 66323a1e152c25b7df7f66deac6dd8d3994de4dc..7a3b4347c9e76b0a1dc4c236a386742b5d56e915 100644
--- a/base/prefs/pref_service.cc
+++ b/base/prefs/pref_service.cc
@@ -240,6 +240,12 @@ bool PrefService::IsManagedPreference(const std::string& pref_name) const {
   return pref && pref->IsManaged();
 }
 
+bool PrefService::IsPreferenceManagedByCustodian(
+    const std::string& pref_name) const {
+  const Preference* pref = FindPreference(pref_name);
+  return pref && pref->IsManagedByCustodian();
+}
+
 bool PrefService::IsUserModifiablePreference(
     const std::string& pref_name) const {
   const Preference* pref = FindPreference(pref_name);
@@ -517,6 +523,10 @@ bool PrefService::Preference::IsManaged() const {
   return pref_value_store()->PrefValueInManagedStore(name_);
 }
 
+bool PrefService::Preference::IsManagedByCustodian() const {
+  return pref_value_store()->PrefValueInSupervisedStore(name_.c_str());
+}
+
 bool PrefService::Preference::IsRecommended() const {
   return pref_value_store()->PrefValueFromRecommendedStore(name_);
 }